Patent Publication Number: US-10777137-B2

Title: Pixel and display device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit of Korean Patent Application No. 10-2018-0041747, filed on Apr. 10, 2018, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND 
     Field 
     Exemplary embodiments of the invention relate generally to a pixel and, more specifically, to pixel including a light emitting device and a display device including the same. 
     Discussion of the Background 
     With an increasing interest in information displays and an increasing demand for portable information media, display devices have been variously developed. 
     More particularly, in recent years, as the demand for a high resolution display device increases, the size of a pixel is becoming smaller while the structure of a circuit included in the pixel become more complicated. 
     The above information disclosed in this Background section is only for understanding of the background of the inventive concepts, and, therefore, it may contain information that does not constitute prior art. 
     SUMMARY 
     A pixel and a display device including the same according to an exemplary embodiment of the present invention is capable of minimizing defects and improving reliability of the display device. 
     Additional features of the inventive concepts will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the inventive concepts. 
     A pixel according to an exemplary embodiment includes a light emitting element, a first transistor connected between a first node and the light emitting element, the first transistor configured to control an amount of current flowing from a first power supply of the first node to a second power supply via the light emitting element, a second transistor connected between a data line and the first transistor, the second transistor configured to be turned on by an i th  first scan signal, wherein i is a natural number of 2 or more, a third transistor connected between the first transistor and the first node, the third transistor configured to be turned on by the i th  first scan signal and comprising a P-type thin film transistor, a fourth transistor connected between the first node and an initialization power supply line to which an initialization power supply is supplied, the fourth transistor configured to be turned on by an i−1 th  scan signal and including an N-type thin film transistor, and a first connection line connected between the third transistor and the fourth transistor, the first connection line configured to electrically connect a semiconductor pattern of the third transistor and a semiconductor pattern of the fourth transistor, in which the first connection line is disposed on the third transistor and the fourth transistor with an insulation layer interposed therebetween, and contacts the semiconductor pattern of each of the third transistor and the fourth transistor through a first contact hole passing through the insulation layer. 
     The semiconductor pattern of the third transistor may be doped with a p-type impurity, and the semiconductor pattern of the fourth transistor may be doped with an n-type impurity. 
     The semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor may be disposed on the same layer of a substrate and are adjacent to each other. 
     The substrate may include an overlap region where the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor overlap with each other, and the first connection line may contact the semiconductor pattern of the third transistor, the semiconductor pattern of the fourth transistor, and the overlap region. 
     The substrate may includes an undoped region, to which the p-type impurity and the n-type impurity are not doped, and disposed between the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor, and the first connection line may contact each of the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor with the undoped region interposed therebetween. 
     The pixel may further include a fifth transistor connected between the initialization power supply line and an anode electrode of the light emitting element, the fifth transistor configured to be turned on by an i th  second scan signal and including an N-type thin film transistor. 
     The i th  first scan signal and the i th  second scan signal may have different levels from each other and may be simultaneously supplied to a corresponding transistor to activate the corresponding transistor. 
     The pixel may further include a sixth transistor connected between a second electrode of the first transistor and the anode electrode of the light emitting element, the sixth transistor configured to be turned off when an emission control signal is supplied to an emission control line, and a seventh transistor connected between the first node and the first power supply and configured to be turned off when the emission control signal is supplied, in which the sixth transistor and the seventh transistor may include a P-type thin film transistor. 
     The pixel may further include a second connection line connected between the fifth transistor and the sixth transistor and configured to electrically connect a semiconductor pattern of the fifth transistor and a semiconductor pattern of the sixth transistor, in which the second connection line may be disposed on the fifth transistor and the sixth transistor with the insulation layer interposed therebetween, and contacts the semiconductor pattern of each of the fifth transistor and the sixth transistor through a second contact hole passing through the insulation layer. 
     The semiconductor pattern of the fifth transistor may be doped with an n-type impurity, and the semiconductor pattern of the sixth transistor is doped with a p-type impurity. 
     The semiconductor pattern of the fifth transistor and the semiconductor pattern of the sixth transistor may be disposed on the same layer of a substrate and are adjacent to each other. 
     The first transistor and the second transistor may include a P-type thin film transistor. 
     A pixel according to another exemplary embodiment includes a light emitting element, a first transistor connected between a first node and the light emitting element, the first transistor configured to control an amount of current flowing from a first power supply of the first node to a second power supply via the light emitting element, a second transistor connected between a data line and the first transistor, the second transistor configured to be turned on by an i th  first scan signal, wherein i is a natural number of 2 or more, a third transistor connected between the first transistor and the first node, the third transistor configured to be turned on by the ith first scan signal, a fourth transistor connected between the first node and an initialization power supply line to which an initialization power supply is supplied, the fourth transistor configured to be turned on by an i−1 th  scan signal, a fifth transistor connected between the first node and the first power supply, the fifth transistor configured to be turned off when an emission control signal is supplied to an emission control line, a sixth transistor connected between a second electrode of the first transistor and an anode electrode of the light emitting element, the sixth transistor configured to be turned off when the emission control signal is supplied, a seventh transistor connected between the initialization power supply line and the anode electrode of the light emitting element, the seventh transistor configured to be turned on by an i th  second scan signal, a first connection line connected between the third transistor and the fourth transistor, the first connection line configured to electrically connect a semiconductor pattern of the third transistor and a semiconductor pattern of the fourth transistor, and a second connection line connected between the sixth transistor and the seventh transistor, the second connection line configured to electrically connect a semiconductor pattern of the sixth transistor and a semiconductor pattern of the seventh transistor, in which the fourth transistor and the seventh transistor include an N-type thin film transistor, and the first, second, third, fifth, sixth transistors include a P-type thin film transistor. 
     The first connection line may be disposed on the third transistor and the fourth transistor with an insulation layer interposed therebetween, and may contact the semiconductor pattern of each of the third transistor and the fourth transistor through a first contact hole passing through the insulation layer, and the second connection line may be disposed on the sixth transistor and the seventh transistor with the insulation layer interposed therebetween, and may contact the semiconductor pattern of each of the sixth transistor and the seventh transistor through a second contact hole passing through the insulation layer. 
     The semiconductor pattern of the fourth transistor and the semiconductor pattern of the seventh transistor may be doped with an n-type impurity, and the semiconductor patterns of the first, second, third, fifth, and sixth transistors may be doped with a p-type impurity. 
     The semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor may be disposed on the same layer of a substrate and are adjacent to each other, and the semiconductor pattern of the sixth transistor and the semiconductor pattern of the seventh transistor may be disposed on the same layer of the substrate and are adjacent to each other. 
     The substrate may include an overlap region where the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor overlap with each other, and the first connection line may contact the semiconductor pattern of the third transistor, the semiconductor pattern of the fourth transistor, and the overlap region. 
     The substrate may include an undoped region, to which the p-type impurity and the n-type impurity are not doped, and disposed between the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor, and the first connection line may contact each of the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor with the undoped region interposed therebetween. 
     A display device according to yet another exemplary embodiment includes a substrate, a plurality of pixels disposed on the substrate and connected to a plurality of scan lines, a plurality of emission control lines, and a plurality of data lines, and a driver configured to drive the scan lines, the emission control lines, and the data lines, in which at least one pixel disposed in an i th  (i is a natural number of 2 or more) horizontal line of the pixels includes a light emitting element, a first transistor connected between a first node and the light emitting element, the first transistor configured to control an amount of current flowing from a first power supply of the first node to a second power supply via the light emitting element, a second transistor connected between a corresponding data line and the first transistor, the second transistor configured to be turned on by an ith first scan signal, a third transistor connected between the first transistor and the first node, the third transistor configured to be turned on by the ith first scan signal and including a P-type thin film transistor, a fourth transistor connected between the first node and an initialization power supply line to which an initialization power supply is supplied, the fourth transistor configured to be turned on by an i−1 th  scan signal and including an N-type thin film transistor, and a first connection line connected between the third transistor and the fourth transistor, the first connection line configured to electrically connect a semiconductor pattern of the third transistor and a semiconductor pattern of the fourth transistor, and in which the first connection line is disposed on the third transistor and the fourth transistor with an insulation layer on the substrate interposed therebetween, and contacts the semiconductor pattern of each of the third transistor and the fourth transistor through a first contact hole passing through the insulation layer. 
     The semiconductor pattern of the third transistor may be doped with a p-type impurity, and the semiconductor pattern of the fourth transistor may be doped with an n-type impurity. 
     The semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor may be disposed on the same layer of a substrate and are adjacent to each other. 
     The substrate may include an overlap region where the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor overlap with each other, and the first connection line may contact the semiconductor pattern of the third transistor, the semiconductor pattern of the fourth transistor, and the overlap region. 
     The substrate may include an undoped region, to which the p-type impurity and the n-type impurity are not doped, and disposed between the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor, and the first connection line may contact each of the semiconductor pattern of the third transistor and the semiconductor pattern of the fourth transistor with the undoped region interposed therebetween. 
     The display device may further include a fifth transistor connected between the initialization power supply line and an anode electrode of the light emitting element, the fifth transistor configured to be turned on by an i th  second scan signal and including an N-type thin film transistor. 
     The i th  first scan signal and the i th  second scan signal may have different levels from each other, and may be simultaneously supplied to a corresponding transistor to activate the corresponding transistor. 
     The display device may further include a sixth transistor connected between a second electrode of the first transistor and the anode electrode of the light emitting element, the sixth transistor configured to be turned off when an emission control signal is supplied to an corresponding emission control line, and a seventh transistor connected between the first node and the first power supply, the seventh transistor configured to be turned off when the emission control signal is supplied, in which the sixth transistor and the seventh transistor may include a P-type thin film transistor. 
     The display device may further include a second connection line connected between the fifth transistor and the sixth transistor, the second connection line configured to electrically connect a semiconductor pattern of the fifth transistor and a semiconductor pattern of the sixth transistor, in which the second connection line may be disposed on the fifth transistor and the sixth transistor with the insulation layer interposed therebetween, and contacts the semiconductor pattern of each of the fifth transistor and the sixth transistor through a second contact hole passing through the insulation layer. 
     The semiconductor pattern of the fifth transistor maybe doped with a n-type impurity, and the semiconductor pattern of the sixth transistor may be doped with an p-type impurity. 
     The semiconductor pattern of the fifth transistor and the semiconductor pattern of the sixth transistor may be disposed on the same layer of a substrate, and are adjacent to each other. 
     The first transistor and the second transistor may include a P-type thin film transistor. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention, and together with the description serve to explain the inventive concepts. 
         FIG. 1  is a plan view of a display device according to an exemplary embodiment. 
         FIG. 2  is a block diagram of pixels and a driver in a display device of  FIG. 1  according to an exemplary embodiment. 
         FIG. 3  is an equivalent circuit diagram of one pixel of the pixels shown in  FIG. 2 . 
         FIG. 4  is a waveform diagram illustrating a driving method of the pixel shown in  FIG. 3  according to an exemplary embodiment. 
         FIG. 5  is a plan view of one pixel shown in  FIG. 3 . 
         FIG. 6  is a cross-sectional view taken along line I-I′ of  FIG. 5 . 
         FIG. 7  is a cross-sectional view taken along line II-II′ of  FIG. 5 . 
         FIG. 8 ,  FIG. 9 ,  FIG. 10 ,  FIG. 11 ,  FIG. 12 ,  FIG. 13 ,  FIG. 14 ,  FIG. 15 ,  FIG. 16 ,  FIG. 17 ,  FIG. 18 , and  FIG. 19  are cross-sectional views sequentially showing a manufacturing method of the display device shown in  FIG. 5 . 
         FIG. 20A  is an enlarged cross-sectional view of the region EA 1  of  FIG. 6 . 
         FIG. 20B  and  FIG. 20C  are cross-sectional views corresponding to the region EA 1  of  FIG. 6 . 
         FIG. 21A  and  FIG. 21B  are graphs showing current characteristics of an existing pixel and a pixel, respectively, according to an exemplary embodiment. 
         FIG. 22  is an enlarged plan view of two pixels included in the display device according to another exemplary embodiment. 
         FIG. 23  is a cross-sectional view taken along line of  FIG. 22 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of various exemplary embodiments or implementations of the invention. As used herein “embodiments” and “implementations” are interchangeable words that are non-limiting examples of devices or methods employing one or more of the inventive concepts disclosed herein. It is apparent, however, that various exemplary embodiments may be practiced without these specific details or with one or more equivalent arrangements. In other instances, well-known structures and devices are shown in block diagram form in order to avoid unnecessarily obscuring various exemplary embodiments. Further, various exemplary embodiments may be different, but do not have to be exclusive. For example, specific shapes, configurations, and characteristics of an exemplary embodiment may be used or implemented in another exemplary embodiment without departing from the inventive concepts. 
     Unless otherwise specified, the illustrated exemplary embodiments are to be understood as providing exemplary features of varying detail of some ways in which the inventive concepts may be implemented in practice. Therefore, unless otherwise specified, the features, components, modules, layers, films, panels, regions, and/or aspects, etc. (hereinafter individually or collectively referred to as “elements”), of the various embodiments may be otherwise combined, separated, interchanged, and/or rearranged without departing from the inventive concepts. 
     The use of cross-hatching and/or shading in the accompanying drawings is generally provided to clarify boundaries between adjacent elements. As such, neither the presence nor the absence of cross-hatching or shading conveys or indicates any preference or requirement for particular materials, material properties, dimensions, proportions, commonalities between illustrated elements, and/or any other characteristic, attribute, property, etc., of the elements, unless specified. Further, in the accompanying drawings, the size and relative sizes of elements may be exaggerated for clarity and/or descriptive purposes. When an exemplary embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order. Also, like reference numerals denote like elements. 
     When an element, such as a layer, is referred to as being “on,” “connected to,” or “coupled to” another element or layer, it may be directly on, connected to, or coupled to the other element or layer or intervening elements or layers may be present. When, however, an element or layer is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element or layer, there are no intervening elements or layers present. To this end, the term “connected” may refer to physical, electrical, and/or fluid connection, with or without intervening elements. Further, the D1-axis, the D2-axis, and the D3-axis are not limited to three axes of a rectangular coordinate system, such as the x, y, and z-axes, and may be interpreted in a broader sense. For example, the D1-axis, the D2-axis, and the D3-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. For the purposes of this disclosure, “at least one of X, Y, and Z” and “at least one selected from the group consisting of X, Y, and Z” may be construed as X only, Y only, Z only, or any combination of two or more of X, Y, and Z, such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms “first,” “second,” etc. may be used herein to describe various types of elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. Thus, a first element discussed below could be termed a second element without departing from the teachings of the disclosure. 
     Spatially relative terms, such as “beneath,” “below,” “under,” “lower,” “above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), and the like, may be used herein for descriptive purposes, and, thereby, to describe one elements relationship to another element(s) as illustrated in the drawings. Spatially relative terms are intended to encompass different orientations of an apparatus in use, operation, and/or manufacture in addition to the orientation depicted in the drawings. For example, if the apparatus in the drawings is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and, as such, the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms, “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Moreover, the terms “comprises,” “comprising,” “includes,” and/or “including,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It is also noted that, as used herein, the terms “substantially,” “about,” and other similar terms, are used as terms of approximation and not as terms of degree, and, as such, are utilized to account for inherent deviations in measured, calculated, and/or provided values that would be recognized by one of ordinary skill in the art. 
     Various exemplary embodiments are described herein with reference to sectional and/or exploded illustrations that are schematic illustrations of idealized exemplary embodiments and/or intermediate structures. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, exemplary embodiments disclosed herein should not necessarily be construed as limited to the particular illustrated shapes of regions, but are to include deviations in shapes that result from, for instance, manufacturing. In this manner, regions illustrated in the drawings may be schematic in nature and the shapes of these regions may not reflect actual shapes of regions of a device and, as such, are not necessarily intended to be limiting. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure is a part. Terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense, unless expressly so defined herein. 
       FIG. 1  is a plan view of a display device according to an exemplary embodiment. 
     Referring to  FIG. 1 , a display device according to an exemplary embodiment may include a substrate SUB, pixels PXL provided on the substrate SUB, a driver provided on the substrate SUB and driving the pixels PXL, and a line unit (not shown) connecting the pixels PXL and the driver. 
     The substrate SUB may include a display region DA and a non-display region NDA. The display region DA may be a region in which the pixels PXL for displaying an image are provided. Each pixel PXL will be described in more detail later. The non-display region NDA may be a region in which the driver for driving the pixels PXL and a portion of a line (not shown) connecting the pixels PXL and the driver are provided. 
     The display region DA may have various shapes. For example, the display region DA may be provided in various shapes, such as a closed polygon including sides made of straight lines, a circle, an ellipse including sides made of curved lines, a semicircle, a semi-ellipse including sides made of straight lines and curved lines, and the like. When the display region DA includes a plurality of regions, each region may also be provided in various shapes, such as a closed polygon including sides of straight lines, a semicircle, a semi-ellipse including sides of curved lines, and the like. In addition, areas of the plurality of regions may be the same as or different from each other. 
     Hereinafter, the display region DA according to an exemplary embodiment will be described as including one region having a quadrangle shape, which includes sides of a straight line. The non-display region NDA may be provided on at least one side of the display region DA. In an exemplary embodiment, the non-display region NDA may surround the display region DA. 
     The pixels PXL may be provided in the display region DA on the substrate SUB, and may be connected to the line. Each pixel PXL may be a minimum unit for displaying an image, and may be provided in plural. 
     The pixels PXL may include a light emitting device, which emits white light and/or color light, and a pixel circuit for driving the light emitting device. The pixel circuit may include at least one transistor connected to the light emitting device. 
     Each pixel PXL may emit at least one of red, green, and blue colors, but is not limited thereto. For example, each pixel PXL may emit at least one of cyan, magenta, yellow, and white colors. The pixels PXL are arranged along rows extending in a first direction DR 1  and columns extending in a second direction DR 2  crossing the first direction DR 1 . However, an arrangement form of the pixels PXL is not particularly limited, and may be arranged in various forms. 
     The driver may supply a signal to each pixel PXL through the line unit, thereby controlling the driving of the pixel PXL. In  FIG. 1 , the line unit is not shown, however, the line unit will be described in more detail later. 
     The driver may include a scan driver SDV for supplying a scan signal to the pixels PXL through a scan line, an emission driver EDV for supplying an emission control signal to the pixels PXL through an emission control line, a data driver DDV for supplying a data signal to the pixels PXL through a data line, and a timing controller. The timing controller may control the scan driver SDV, the emission driver EDV, and the data driver DDV. 
     The scan driver SDV may be disposed in a vertical portion of the non-display region NDA. The vertical portion of the non-display region NDA may be provided in a pair spaced apart from each other along the width direction of the display region DA. As such, the scan driver SDV may be disposed in at least one of the vertical portions of the non-display region NDA. The scan driver SDV may extend in the longitudinal direction of the non-display region NDA. 
     The emission driver EDV may also be disposed in a vertical portion of the non-display region NDA, similarly to the scan driver SDV. The emission driver EDV may be disposed in at least one of the vertical portions of the non-display region NDA. The emission driver EDV may extend in the longitudinal direction of the non-display region NDA. 
     In an exemplary embodiment, the scan driver SDV may be provided at one of the vertical portions, and the emission driver EDV may be provided at the other of the vertical portions. However, the inventive concepts are not limited thereto, and the scan driver SDV and the emission driver EDV may be disposed adjacent to each other and formed only at one of the vertical portions of the non-display region NDA. 
     The data driver DDV may be disposed in the non-display region NDA. More particularly, the data driver DDV may be disposed in a horizontal portion of the non-display region NDA. The data driver DDV may extend in the width direction of the non-display region NDA. The inventive concepts are not limited to particular positions of the drivers, and the positions of the scan driver SDV, the emission driver EDV, and/or the data driver DDV may be variously changed as needed. 
     The timing controller may be connected to the scan driver SDV, the emission driver EDV, and the data driver DDV through lines in various ways. The position of the timing controller is not particularly limited. For example, the timing controller may be mounted on a printed circuit board and may be connected to the scan driver SDV, the emission driver EDV, and the data driver DDV through a flexible printed circuit board. The printed circuit board may be disposed at various positions, such as one side of the substrate SUB, a backside of the substrate SUB, and the like. 
       FIG. 2  is a block diagram of pixels and a driver in a display device of  FIG. 1  according to an exemplary embodiment. 
     Referring to  FIGS. 1 and 2 , a display device according to an exemplary embodiment may include pixels PXL, a driver, and a line unit. 
     The driver may include a scan driver SDV, an emission driver EDV, a data driver DDV, and a timing controller TC. The positions of the scan driver SDV, the emission driver EDV, the data driver DDV, and the timing controller TC shown in  FIG. 2  may be varied to be disposed at other positions in the display device when a real display device is actually implemented. 
     The line unit may include a scan line, a data line, an emission control line, a power supply line PL, and an initialization power supply line disposed in the display region DA to supply a signal to each pixel PXL from the driver. 
     The scan line may include a plurality of scan lines S 1  to Sn, the emission control line may include a plurality of emission control lines E 1  to En, and the data lines may include a plurality of data lines D 1  to Dm. 
     The pixels PXL may include a light emitting device, which emits light, and a pixel circuit for driving the light emitting device. The pixel circuit may include at least one transistor connected to the light emitting device. The pixels PXL may be provided in the display region DA. Each pixel PXL may receive a data signal from a data line corresponding thereto when a scan signal is supplied from a scan line corresponding thereto. Each pixel PXL receiving the data signal may control the amount of current amount flowing from the first power supply ELVDD provided through the power supply line PL to the second power supply ELVSS through an light emitting device. 
     The scan driver SDV may supply the scan signal to the scan lines S 1  to Sn in response to the first gate control signal GCS 1  from the timing controller TC. For example, the scan driver SDV may sequentially supply the scan signal to the scan lines S 1  to Sn. When the scan signal is sequentially supplied to the scan lines S 1  to Sn, the pixels PXL may be sequentially selected in horizontal line units. 
     The emission driver EDV may apply the emission control signal to the emission control lines E 1  to En in response to the second gate control signal GCS 2  from the timing controller TC. For example, the emission controller EDV may sequentially supply the emission control signals to the emission control lines E 1  to En. 
     As used herein, the emission control signal may be set to have a greater width than the scan signal. For example, the emission control signal supplied to the i th  emission control line Ei (i is a natural number) may overlap at least one portion of a scan signal supplied to the i−1 th  scan line Si−1 and a scan signal supplied to the i th  scan line Si. In addition, the emission control signal may be set to a gate-off voltage (e.g., a high voltage) so that the transistor included in the pixels PXL may be turned off, and the scan signal may be set to a gate-on voltage (e.g., a low voltage) so that the transistor included in the pixels PXL may be turned on. 
     The data driver DDV may supply the data signal to the data lines D 1  to Dm in response to a data control signal DCS. The data signal supplied to the data lines D 1  to Dm may be supplied to the pixels PXL selected by the scan signal. 
     The timing controller TC may supply a gate control signals GCS 1  and GCS 2  based on timing signals supplied from the outside to the scan driver SDV and the emission driver EDV, and may supply the data control signal DCS to the data driver DDV. Each of the gate control signals GCS 1  and GCS 2  may include a start pulse and clock signals. The start pulse controls the timing of the first scan signal or the first emission control signal. The clock signals are used to shift the start pulse. 
     The data control signal DCS includes a source start pulse and clock signals. The source start pulse are used to control the sampling start time of the data, and the clock signals are used to control the sampling operation. 
       FIG. 3  is an equivalent circuit diagram of one pixel of the pixels shown in  FIG. 2 . 
       FIG. 3  shows one pixel connected to the j th  data line Dj, the i−1 th  scan line Si−1, the i th  scan line Si, and the i+1 th  scan line Si+1. Referring to  FIGS. 2 and 3 , the pixel PXL according to an exemplary embodiment may include a light emitting device OLED, and a pixel circuit PC connected to the light emitting device OLED to drive the light emitting device OLED. Herein, the pixel circuit PC may include first to seventh transistors T 1  to T 7 , and a storage capacitor Cst. 
     An anode electrode of the light emitting device OLED may be connected to the first transistor T 1  via the sixth transistor T 6 , and a cathode electrode of the light emitting device OLED may be connected to the second power supply ELVSS. 
     The light emitting device OLED may generate light having a predetermined luminance corresponding to the amount of current supplied from the first transistor T 1 . The first power supply ELVDD supplied to the power supply line PL may be set to a higher voltage than the second power supply ELVSS, so that current may flow through the light emitting device OLED. 
     A source electrode of the first transistor T 1  (i.e., a driving transistor) is connected to the first power supply ELVDD via the fifth transistor T 5 , and a drain electrode of the first transistor T 1  is connected to the anode electrode of the light emitting device OLED via the sixth transistor T 6 . The first transistor T 1  may be a P-type thin film transistor. 
     The first transistor T 1  controls the current amount flowing from the first power supply ELVDD to the second power supply ELVSS via the light emitting device OLED corresponding to the voltage of the first node N 1 , which is a gate electrode thereof. 
     The second transistor T 2  (i.e., a switching transistor) is connected between the j th  data line Dj and the source electrode of the first transistor T 1 . The gate electrode of the second transistor T 2  is connected to the i th  first scan line Sia. The second transistor T 2  may be a P-type thin film transistor. When a scan signal is supplied to the i th  first scan line Sia, the second transistor T 2  is turned on to electrically connect the j th  data line Dj to the source electrode of the first transistor T 1 . 
     The third transistor T 3  is connected between the drain electrode of the first transistor T 1  and the first node N 1 . A gate electrode of the third transistor T 3  is connected to the i th  first scan line Sia. The third transistor T 3  may be a P-type thin film transistor. When a scan signal is supplied to the i th  scan line Si, the third transistor T 3  is turned on to electrically connect the drain electrode of the first transistor T 1  to the first node N 1 . Therefore, when the third transistor T 3  is turned on, the first transistor T 1  is connected in a diode form. 
     The fourth transistor T 4  is connected between the first node N 1  and the initialization power supply Vint. A gate electrode of the fourth transistor T 4  is connected to the i−1 th  scan line Si−1. When a scan signal is supplied to the i−1 th  scan line Si−1, the fourth transistor T 4  is turned on to supply the voltage of the initialization power supply Vint to the first node N 1 . 
     In an exemplary embodiment, the fourth transistor T 4  may be a N-type thin film transistor. The N-type thin film transistor may have better off current characteristic than the P-type thin film transistor. When the fourth transistor T 4  is formed of an N-type thin film transistor, a leakage current flowing from the first node N 1  to the initialization power supply Vint may be minimized, thereby displaying an image with a desired luminance. 
     The fifth transistor T 5  is connected between the first power supply ELVDD and the source electrode of the first transistor T 1 . A gate electrode of the fifth transistor T 5  is connected to the i th  emission control line Ei. The fifth transistor T 5  may be a P-type thin film transistor. The fifth transistor T 5  is turned off when the emission control signal is supplied to the i th  emission control line Ei, and is turned on in other cases. 
     The sixth transistor T 6  is connected between the drain electrode of the first transistor T 1  and the anode electrode of the light emitting device OLED. A gate electrode of the sixth transistor T 6  is connected to the i th  emission control line Ei. The sixth transistor T 6  may be a P-type thin film transistor. The sixth transistor T 6  is turned off when the emission control signal is supplied to the i th  emission control line Ei, and is turned on in other cases. 
     The seventh transistor T 7  is connected between the initialization power supply Vint and the anode electrode of the light emitting device OLED. A gate electrode of the seventh transistor T 7  is connected to the i th  second scan line Sib. When a scan signal is supplied to the i th  second scan line Sib, the seventh transistor T 7  is turned on to supply the voltage of the initialization power supply Vint to the anode electrode of the light emitting device OLED. 
     The seventh transistor T 7  may be an N-type thin film transistor. Since the seventh transistor T 7  is formed of an N-type thin film transistor, a leakage current supplied from the anode electrode of the light emitting device OLED to the initialization power supply Vint during an emission period of the light emitting device OLED may be minimized. 
     As described above, if the leakage current supplied from the anode electrode of the light emitting device OLED to the initialization power supply Vint is minimized, the light emitting device OLED may generate light of desired luminance. 
     The storage capacitor Cst is connected between the first power supply ELVDD and the first node N 1 . The storage capacitor Cst stores a voltage corresponding to the data signal and the threshold voltage of the first transistor T 1 . 
     Meanwhile, the initialization power supply Vint may be set to a lower voltage than the data signal. When the voltage of the initialization power supply Vint is supplied to the anode electrode of the light emitting device OLED, a parasitic capacitor of the light emitting device OLED may be discharged. 
     When the parasitic capacitor of the light emitting device OLED is discharged by the initialization power supply Vint, the light emitting device OLED may be set to a non-emission state even if a leakage current is supplied from the first transistor T 1 . More particularly, the leakage current from the first transistor T 1  pre-charges the parasitic capacitor of the light emitting device OLED, so that the parasitic capacitor of the light emitting device OLED may maintain the non-emission state. 
     The pixel PXL may include first and second contact portions CNP 1  and CNP 2  indicating regions in which different types of thin film transistors are in contact with each other. 
     The first contact portion CNP 1  may be disposed between the third transistor T 3  formed of a P-type thin film transistor and the fourth transistor T 4  formed of an N-type thin film transistor. The second contact CNP 2  may be disposed between the sixth transistor T 6  formed of the P-type thin film transistor and the seventh transistor T 7  formed of the N-type thin film transistor. 
     In an exemplary embodiment, the fourth transistor T 4  and the seventh transistor T 7  may be formed the N-type thin film transistor and the other transistors T 1 , T 2 , T 3 , T 5  and T 6  may be formed of the P-type thin film transistor. 
     Hereinafter, the operation of the pixel according to an exemplary embodiment will be described with reference to  FIG. 4 . 
       FIG. 4  is a waveform diagram illustrating a driving method of the pixel shown in  FIG. 3  according to an exemplary embodiment. 
     Referring to  FIGS. 3 and 4 , the emission control signal (of high level) is supplied to the i th  emission control line Ei, whereby the fifth and sixth transistors T 5  and T 6  formed of the P-type thin film transistor are turned off. 
     When the fifth and sixth transistors T 5  and T 6  are turned off, an electrical connection between the first power supply ELVDD and the first node N 1  may be cut off. Therefore, the pixel PXL may be set to the non-emission state during the period when the emission control signal is supplied. 
     Then, an i−1 th  scan signal (of high level) is supplied to an i−1 th  scan line Si−1. When the i−1 th  scan signal is supplied to the i−1 th  scan line Si−1, the fourth transistor T 4 , which is an N-type thin film transistor, is turned on. 
     When the fourth transistor T 4  is turned on, the voltage of the initialization power supply Vint is supplied to the first node N 1 . After the voltage of the initialization power supply Vint is supplied to the first node N 1 , the i th  first scan signal (of low level) is supplied to the i th  first scan line Sia and the i th  second scan signal (of high level) is supplied to the i th  second scan line Sib. 
     When the i th  second scan signal is supplied to the i th  second scan line Sib, the seventh transistor T 7 , which is an N-type thin film transistor, is turned on. When the seventh transistor T 7  is turned on, the voltage of the initialization power supply Vint is supplied to the anode electrode of the light emitting device OLED. When the voltage of the initialization power supply Vint is supplied to the anode electrode of the light emitting device OLED, the parasitic capacitor of the light emitting device OLED is discharged. 
     When the i th  first scan signal is supplied to the i th  first scan line Sia, the second and third transistors T 2  and T 3 , which are P-type thin film transistors, are turned on. 
     When the second transistor T 2  is turned on, the j th  data line Dj and the source electrode of the first transistor T 1  are electrically connected to each other. In this case, a data signal from the j th  data line Dj is supplied to the first transistor T 1 . 
     When the third transistor T 3  is turned on, the first node N 1  and the drain electrode of the first transistor T 1  are electrically connected to each other. In this case, the first transistor T 1  may be connected in a diode form. At this time, since the first node N 1  is initialized to the voltage of the initialization power supply Vint lower than the data signal, the first transistor T 1  is turned on. 
     When the first transistor T 1  is turned on, the data signal is supplied to the first node N 1  via the first transistor T 1 . At this time, the first node N 1  is set to a voltage corresponding to the data signal and the threshold voltage of the first transistor T 1 . 
     The storage capacitor Cst stores the voltage applied to the first node N 1 . 
     After the voltage of the first node N 1  is stored in the storage capacitor Cst, the supply of the i th  emission control signal to the i th  emission control line Ei is stopped. When the supply of the i th  emission control signal to the i th  emission control line Ei is stopped, the fifth and sixth transistors T 5  and T 6  are turned on. 
     When the fifth transistor T 5  is turned on, the voltage of the first power supply ELVDD is supplied to the source electrode of the first transistor T 1 . At this time, the first transistor T 1  generates a driving current. 
     When the sixth transistor T 6  is turned on, the first transistor T 1  and the light emitting device OLED may be electrically connected to each other. At this time, the driving current generated by the first transistor T 1  is supplied to the light emitting device OLED, and the light emitting device OLED outputs light having intensity corresponding to the driving current. 
     In an exemplary embodiment, a scan signal supplied to the i th  first scan line Sia (hereinafter, referred to as a ‘first scan signal’) and a scan signal supplied to the i th  second scan line Sib (hereinafter, referred to as a ‘second scan signal’) have different levels, and are simultaneously supplied to the corresponding transistors so that the corresponding transistors may be turned on, i.e., activated. 
     For example, the first scan signal of a low level may be supplied to the second and third transistors T 2  and T 3 , and the second scan signal of a high level may be simultaneously supplied to the seventh transistor T 7 . Accordingly, the second and third transistors T 2  and T 3  and the seventh transistor T 7  may be simultaneously turned on. 
     In an exemplary embodiment, the second scan signal has the same level as a scan signal supplied to the i−1 th  scan line Si−1 (hereinafter, referred to as ‘third scan signal’), and are simultaneously supplied to the corresponding transistors so that the corresponding transistors may be turned on, i.e., activated. 
     For example, the second scan signal of a high level may be supplied to the seventh transistor T 7  and the third scan signal of a high level may be simultaneously supplied to the fourth transistor T 4 . Accordingly, the fourth transistor T 4  and the seventh transistor T 7  may be simultaneously turned on. 
       FIG. 5  is a plan view of one pixel shown in  FIG. 3 ,  FIG. 6  is a cross-sectional view taken along line I-I′ of  FIG. 5 , and  FIG. 7  is a cross-sectional view taken along line II-II′ of  FIG. 5 . 
     The pixel PXL according to an exemplary embodiment is disposed in the i th  row and the j th  column of the display region, and  FIGS. 5 to 7  show three scan lines Si−1, Sia and Sib, an emission control line Ei, the power supply line PL, and data line Dj connected to the one pixel PXL. 
     In  FIGS. 5 to 7 , the scan line of the i−1 th  row is referred to as “the i−1 th  scan line Si−1”, the first scan line of the i th  row is referred to as “the i th  first scan line Sia”, the second scan line of the i th  row is referred to as “the i th  second scan line Sib”, the emission control line of the i th  row is referred to as “an emission control line Ei”, the data line of the j th  column is referred to as “a data line Dj”, and the power supply line of the j th  column is referred to as “the power supply line PL”. 
     Referring to  FIGS. 1 to 7 , a display device according to an exemplary embodiment may include a substrate SUB, a line unit, and the pixel PXL. 
     The substrate SUB may include a transparent insulating material to transmit light. In addition, the substrate SUB may be a rigid substrate or a flexible substrate. The rigid substrate may include a glass substrate, a quartz substrate, a glass ceramic substrate, and a crystalline glass substrate. 
     The flexible substrate may include a film substrate and a plastic substrate including a polymeric organic material. For example, the flexible substrate may include at least one of polyethersulfone (PES), polyacrylate, polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate (PAR), polyimide (PI), polycarbonate (PC), triacetate cellulose (TAC), and cellulose acetate propionate (CAP). In addition, the flexible substrate may include fiberglass reinforced plastic (FRP). 
     The material of the substrate SUB may preferably have resistance (or heat resistance) against a high processing temperature from the manufacturing process of the display device. In an exemplary embodiment, the substrate SUB may be entirely or partially flexible. 
     The line unit may provide a signal to the pixel PXL, and may include a scan line Si−1, Sia, Sib, a data line Dj, an emission control line Ei, a power supply lines PL, and an initialization power supply line IPL. 
     The scan lines Si−1, Si, and Si+1 may extend in a first direction DR 1 . The scan lines Si−1, Sia and Sib may include the i−1 th  scan line Si−1, the i th  first scan line Sia, and the i th  second scan line Sib, sequentially arranged in a second direction DR 2  crossing the first direction DR 1 . 
     A scan signal may be supplied to the scan lines Si−1, Sia, and Sib. For example, the i−1 th  scan signal may be supplied to the i−1 th  scan line Si−1, the i th  first scan signal may be supplied to the i th  first scan line Sia, and the i th  second scan signal may be supplied to the i th  second scan line Sib. The i th  first scan signal and the i th  second scan signal may be simultaneously supplied to the corresponding scan lines. 
     The emission control line Ei extends in the first direction DR 1 , is disposed between the i th  first scan line Sia and the i th  second scan line Sib, and is spaced apart from the i th  first scan line Sia and the i th  second scan line Sib. An emission control signal is supplied to the emission control line Ei. 
     The data lines Dj may extend in the second direction DR 2  and a data signal may be supplied to the data line Dj. The power supply line PL may extend in the second direction DR 2 . The power supply line PL may be spaced apart from the data line Dj. The first power supply ELVDD may be supplied to the power supply line PL. 
     The initialization power supply line IPL may extend in the first direction DR 1 . The initialization power supply line IPL may be provided between the i th  second scan line Sib and the i−1 th  scan line Si−1 of the pixel in the next row. An initialization power supply Vint may be supplied to the initialization power supply line IPL. 
     The pixels PXL may include a light emitting device OLED, which emits light, and a pixel circuit PC for driving the light emitting device OLED. The pixel circuit PC may include first to seventh transistors T 1  to T 7 , and a storage capacitor Cst. 
     In an exemplary embodiment, the first to third transistors T 1  to T 3  and the fifth and sixth transistors T 5  and T 6  may be formed of P type thin film transistors. The fourth transistor T 4  and the seventh transistor T 7  may be formed of N-type thin film transistors. 
     The first transistor T 1  may include the first gate electrode GE 1 , the first active pattern ACT 1 , the first source electrode SE 1 , the first drain electrode DE 1 , and the first connection line CNL 1 . The first gate electrode GE 1  may be connected to both the third drain electrode DE 3  of the third transistor T 3  and the fourth drain electrode DE 4  of the fourth transistor T 4 . 
     The first connection line CNL 1  may connect among the first gate electrode GE 1 , the third drain electrode DE 3 , and the fourth drain electrode DE 4 . One end of the first connection line CNL 1  may be connected to the first gate electrode GE 1  through the first contact hole CH 1 , and the other end thereof may be connected to both the third drain electrode DE 3  and the fourth source electrode SE 4  through the second contact hole CH 2 . 
     In an exemplary embodiment, the first active pattern ACT 1 , the first source electrode SE 1 , and the first drain electrode DE 1  may be formed of a semiconductor layer not doped with impurity or doped with impurity. 
     For example, the first source electrode SE 1  and the first drain electrode DE 1  may be formed of a semiconductor layer doped with impurity, and the first active pattern ACT 1  may be formed of a semiconductor layer not doped with impurity. As used herein, the impurity may include a p-type impurity. 
     The first active pattern ACT 1  has a bar shape extending in a predetermined direction and may have a shape bent multiple times in the extended longitudinal direction. The first active pattern ACT 1  may overlap the first gate electrode GE 1  in a plane view. Since the first active pattern ACT 1  is formed long, a channel region of the first transistor T 1  may also be formed long. 
     Accordingly, a driving range of a gate voltage supplied to the first transistor T 1  is widened. Therefore, a gray scale of light emitted from the organic light emitting diode OLED may be finely controlled. 
     The first source electrode SE 1  may be connected to one end of the first active pattern ACT 1 . In addition, the first source electrode SE 1  may be connected to the second drain electrode DE 2  of the second transistor T 2  and the fifth drain electrode DE 5  of the fifth transistor T 5 . The first drain electrode DE 1  may be connected to the other end of the first active pattern ACT 1 . In addition, the first drain electrode DE 1  may be connected to the third source electrode SE 3  of the third transistor T 3  and the sixth source electrode SE 6  of the sixth transistor T 6 . 
     The second transistor T 2  may include the second gate electrode GE 2 , the second active pattern ACT 2 , the second source electrode SE 2 , and the second drain electrode DE 2 . The second gate electrode GE 2  may be connected to the i th  first scan line Sia. The second gate electrode GE 2  may be provided in a portion of the i th  first scan line Sia or in a shape protruding from the i th  first scan line Sia. 
     In an exemplary embodiment, the second active pattern ACT 2 , the second source electrode SE 2 , and the second drain electrode DE 2  may be formed of a semiconductor layer not doped with impurity or doped with impurity. 
     For example, the second source electrode SE 2  and the second drain electrode DE 2  may be formed of a semiconductor layer doped with impurity, and the second active pattern ACT 2  may be a semiconductor layer not doped with the impurity. The impurity may include a p-type impurity. 
     The second active pattern ACT 2  corresponds to a portion overlapping the second gate electrode GE 2 . One end of the second source electrode SE 2  is connected to the second active pattern ACT 2 , and the other end thereof is connected to the data line Dj through the sixth contact hole CH 6 . One end of the second drain electrode DE 2  is connected to the second active pattern ACT 2 , and the other end thereof is connected to the first source electrode SE 1  of the first transistor T 1  and the fifth drain electrode DE 5  of the fifth transistor T 5 . 
     The third transistor T 3  may be provided with a double gate structure to prevent a leakage current. That is, the third transistor T 3  may include the third-a transistor T 3   a  and the third-b transistor T 3   b.  The third-a transistor T 3   a  may include the third-a gate electrode GE 3   a,  the third-a active pattern ACT 3   a,  the third-a source electrode SE 3   a,  and the third-a drain electrode DE 3   a.  The third-b transistor T 3   b  may include the third-b gate electrode GE 3   b,  the third-b active pattern ACT 3   b,  the third-b source electrode SE 3   b,  and the third-b drain electrode DE 3   b.    
     In an exemplary embodiment, for convenience of description, the third-a gate electrode GE 3   a  and the third-b gate electrode GE 3   b  are referred to as the third gate electrode GE 3 , the third-a active pattern ACT 3   a  and the third-b active pattern ACT 3   b  are referred to as the third active pattern ACT 3 , the third-a source electrode SE 3   a  and the third-b source electrode SE 3   b  are referred to as the third source electrode SE 3 , and the third-a drain electrode DE 3   a  and the third-b drain electrode DE 3   b  are referred to as the third drain electrode DE 3 . 
     The third gate electrode GE 3  may be connected to the i th  first scan line Sia. The third gate electrode GE 3  is provided in a portion of the i th  first scan line Sia or in a shape protruding from the i th  first scan line Sia. 
     The third active pattern ACT 3 , the third source electrode SE 3 , and the third drain electrode DE 3  may be formed of a semiconductor layer not doped with impurity or doped with impurity. For example, the third source electrode SE 3  and the third drain electrode DE 3  may be formed of a semiconductor layer doped with impurity, and the third active pattern ACT 3  may be formed of a semiconductor layer not doped with impurity. The third active pattern ACT 3  corresponds to a portion overlapping the third gate electrode GE 3 . The impurity may include a p-type impurity. 
     One end of the third source electrode SE 3  may be connected to the third active pattern ACT 3 . The other end of the third source electrode SE 3  may be connected to the first drain electrode DE 1  of the first transistor T 1  and the sixth source electrode SE 6  of the sixth transistor T 6 . One end of the third drain electrode DE 3  may be connected to the third active pattern ACT 3 . The other end of the third drain electrode DE 3  may be connected to the fourth source electrode SE 4  of the fourth transistor T 4 . In addition, the third drain electrode DE 3  may be connected to the first gate electrode GE 1  of the first transistor T 1  through the first connection line CNL 1 , the second contact hole CH 2 , and the first contact hole CH 1 . 
     The fourth transistor T 4  may be provided with a double gate structure to prevent a leakage current. More particularly, the fourth transistor T 4  may include the fourth-a transistor T 4   a  and the fourth-b transistor T 4   b.    
     The fourth-a transistor T 4   a  may include the fourth-a gate electrode GE 4   a,  the fourth-a active pattern ACT 4   a,  the fourth-a source electrode SE 4   a,  and the fourth-a drain electrode DE 4   a.  The fourth-b transistor T 4   b  may include the fourth-b gate electrode GE 4   b,  the fourth-b active pattern ACT 4   b,  the fourth-b source electrode SE 4   b,  and the fourth-b drain electrode DE 4   b.    
     In an exemplary embodiment, for convenience of description, the fourth-a gate electrode GE 4   a  and the fourth-b gate electrode GE 4   b  are referred to as the fourth gate electrode GE 4 , the fourth-a active pattern ACT 4   a  and the fourth-b active pattern ACT 4   b  are referred to as the fourth active pattern ACT 4 , the fourth-a source electrode SE 4   a  and the fourth-b source electrode SE 4   b  are referred to as the fourth source electrode SE 4 , and the fourth-a drain electrode DE 4   a  and the fourth-b drain electrode DE 4   b  are referred to as the fourth drain electrode DE 4 . 
     The fourth gate electrode GE 4  may be connected to the i−1 th  scan line Si−1. The fourth gate electrode GE 4  may be provided in a portion of the i−1 th  scan line Si−1 or in a shape protruding from the i−1 th  scan line Si−1. The fourth active pattern ACT 4 , the fourth source electrode SE 4 , and the fourth drain electrode DE 4  may be formed of a semiconductor layer not doped with impurity or doped with impurity. 
     For example, the fourth source electrode SE 4  and the fourth drain electrode DE 4  may be formed of a semiconductor layer doped with impurity, and the fourth active pattern ACT 4  may be formed of a semiconductor layer not doped with impurity. The fourth active pattern ACT 4  corresponds to a portion overlapping the fourth gate electrode GE 4 . The impurity may include an n-type impurity. 
     One end of the fourth drain electrode DE 4  may be connected to the fourth active pattern ACT 4 . The other end of the fourth drain electrode DE 4  may be connected to the initialization power supply line IPL of the pixel PXL in the i−1 th  row and the seventh drain electrode DE 7  of the seventh transistor T 7  of the pixel PXL in the i−1 th  row. 
     An auxiliary connection line AUX may be provided between the fourth drain electrode DE 4  and the initialization power supply line IPL. 
     One end of the auxiliary connection line AUX may be connected to the fourth drain electrode DE 4  through the ninth contact hole CH 9 . The other end of the auxiliary connection line AUX may be connected to the initialization power supply line IPL of the pixel PXL in the i−1 th  row through the eighth contact hole CH 8  of the pixel PXL in the i−1 th  row. 
     One end of the fourth source electrode SE 4  may be connected to the fourth active pattern ACT 4 . The other end of the fourth source electrode SE 4  may be connected to the third drain electrode DE 3  of the third transistor T 3 . Specifically, the fourth-b source electrode SE 4   b  included in the fourth source electrode SE 4  is connected to the third-b drain electrode DE 3   b  included in the third drain electrode DE 3 . 
     In addition, the fourth source electrode SE 4  is connected to the first gate electrode GE 1  of the first transistor T 1  through the first connection line CNL 1 , the second contact hole CH 2 , and the first contact hole CH 1 . 
     The fifth transistor T 5  may include the fifth gate electrode GE 5 , the fifth active pattern ACT 5 , the fifth source electrode SE 5 , and the fifth drain electrode DE 5 . The fifth gate electrode GE 5  may be connected to the emission control line Ei. The fifth gate electrode GE 5  may be provided in a portion of the emission control line Ei or may be provided in a shape protruding from the emission control line Ei. 
     The fifth active pattern ACT 5 , the fifth source electrode SE 5 , and the fifth drain electrode DE 5  may be formed of a semiconductor layer not doped with impurity or doped with impurity. For example, the fifth source electrode SE 5  and the fifth drain electrode DE 5  may be formed of a semiconductor layer not doped with impurity. The fifth active pattern ACT 5  corresponds to a portion overlapping the fifth gate electrode GE 5 . The impurity may include a p-type impurity. 
     One end of the fifth source electrode SE 5  may be connected to the fifth active pattern ACT 5 . The other end of the fifth source electrode SE 5  may be connected to the power supply line PL through the fifth contact hole CH 5 . One end of the fifth drain electrode DE 5  may be connected to the fifth active pattern ACT 5 . The other end of the fifth drain electrode DE 5  may be connected to the first source electrode SE 1  of the first transistor T 1  and the second drain electrode DE 2  of the second transistor T 2 . 
     The sixth transistor T 6  may include the sixth gate electrode GE 6 , the sixth active pattern ACT 6 , the sixth source electrode SE 6 , and the sixth drain electrode DE 6 . The sixth gate electrode GE 6  may be connected to the emission control line Ei. The sixth gate electrode GE 6  may be provided in a portion of the emission control line Ei or may be provided in a shape protruding from the emission control line Ei. 
     The sixth active pattern ACT 6 , the sixth source electrode SE 6 , and the sixth drain electrode DE 6  are formed of a semiconductor layer, to which impurity is not doped or impurity is doped. For example, the sixth source electrode SE 6  and the sixth drain electrode DE 6  may be formed of a semiconductor layer doped with the impurity, and the sixth active pattern ACT 6  may be formed of a semiconductor layer not doped with the impurity. The sixth active pattern ACT 6  corresponds to a portion overlapping the sixth gate electrode GE 6 . Herein, the impurity may include a p-type impurity. 
     One end of the sixth source electrode SE 6  may be connected to the sixth active pattern ACT 6 . The other end of the sixth source electrode SE 6  may be connected to the first drain electrode DE 1  of the first transistor T 1  and the third source electrode SE 3  of the third transistor T 3 . One end of the sixth drain electrode DE 6  may be connected to the sixth active pattern ACT 6 . The other end of the sixth drain electrode DE 6  may be connected to a seventh source electrode SE 7  of the seventh transistor T 7 . 
     The seventh transistor T 7  may include the seventh gate electrode GE 7 , the seventh active pattern ACT 7 , the seventh source electrode SE 7 , and the seventh drain electrode DE 7 . The seventh gate electrode GE 7  may be connected to the i th  second scan line Sib. The seventh gate electrode GE 7  may be provided in a portion of the i th  second scan line Sib or in a shape protruding from the i th  second scan line Sib. 
     The seventh active pattern ACT 7 , the seventh source electrode SE 7 , and the seventh drain electrode DE 7  may be formed of a semiconductor layer not doped with impurity or doped with impurity. For example, the seventh source electrode SE 7  and the seventh drain electrode DE 7  may be formed of a semiconductor layer doped with the impurity and the seventh active pattern ACT 7  may be formed of a semiconductor layer not doped with the impurity. Herein, the impurity may include an n-type impurity. 
     The seventh active pattern ACT 7  corresponds to a portion overlapping the seventh gate electrode GE 7 . One end of the seventh source electrode SE 7  may be connected to the seventh active pattern ACT 7 . The other end of the seventh source electrode SE 7  may be connected to the sixth drain electrode DE 6  of the sixth transistor T 6 . One end of the seventh drain electrode DE 7  may be connected to the seventh active pattern ACT 7 . The other end of the seventh drain electrode DE 7  may be connected to the initialization power supply line IPL. 
     In addition, the seventh drain electrode DE 7  may be connected to the fourth source electrode SE 4  of the fourth transistor T 4  of the pixel PXL in the i+1 th  row. Specifically, the seventh drain electrode DE 7  may be connected to a fourth-a drain electrode DE 4   a  included in the fourth drain electrode DE 4 . 
     The seventh drain electrode DE 7  and the fourth-a drain electrode DE 4   a  of the fourth transistor T 4  may be connected to each other through the auxiliary line AUX, the eighth contact hole CH 8 , and the ninth contact hole CH 9 . 
     The storage capacitor Cst may include a lower electrode LE and an upper electrode UE. The lower electrode LE may be formed of the first gate electrode GE 1  of the first transistor T 1 . The upper electrode UE may overlap the lower electrode LE and may cover the lower electrode LE in a plane view. A capacitance of the storage capacitor Cst may increase by enlarging an overlapping area between the upper electrode UE and the lower electrode LE. The upper electrode UE may extend in the first direction DR 1 . 
     In an exemplary embodiment, a voltage of the same level as a voltage of the first power supply ELVDD may be supplied to the upper electrode UE. The upper electrode UE may have an opening OPN in a region where the first contact hole CH 1 , through which the first gate electrode GE 1  and the first connection line CNL 1  are connected, is formed. 
     The light emitting device OLED may include the first electrode AD, the second electrode CD, and an emission layer EML provided between the first electrode AD and the second electrode CD. 
     The first electrode AD may be provided in an emission region corresponding to the pixel PXL. The first electrode AD may be connected to the seventh source electrode SE 7  of the seventh transistor T 7  and the sixth drain electrode DE 6  of the sixth transistor T 6  through the seventh contact hole CH 7 , the tenth contact hole CH 10 , and the eleventh contact hole CH 11 . 
     The second connection line CNL 2  and a bridge pattern BRP may be provided between the seventh contact hole CH 7  and the tenth contact hole CH 10 , so that the sixth drain electrode DE 6  and the seventh source electrode are connected to the first electrode AD. 
     Meanwhile, the pixel PXL may be divided into a first region A 1  including a semiconductor layer doped with the n-type impurity, and a second region A 2  excluding the first region A 1 . The second region A 2  may include a semiconductor layer doped with the p-type impurity. 
     In a plan view, the fourth transistor T 4  and the seventh transistor T 7  may be provided in the first region A 1 . In addition, the first to third transistors T 1  to T 3  and the fifth and sixth transistors T 5  and T 6  may be provided in the second region A 2  in a plan view. 
     The first contact portion CNP 1  and the second contact portion CNP 2  may be disposed between the first region A 1  and the second region A 2 . 
     In an exemplary embodiment, the first contact portion CNP 1  may refer to a region where the third-b drain electrode DE 3   b  doped with the p-type impurity contacts the fourth-4 source electrode SE 4   b  doped with the n-type impurity. At this time, the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  may be provided in the same layer on the same plane, but the inventive concepts are not limited thereto. 
     The first connection line CNL 1  may be disposed at the first contact portion CNP 1 . As described above, the first connection line CNL 1  may contact the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  through the second contact hole CH 2 . 
     More specifically, one side of the lower surface of the first connection line CNL 1  may contact the third-b drain electrode DE 3   b,  and the other side of the lower surface of the first connection line CNL 1  may contact the fourth-b source electrode SE 4   b.    
     In an exemplary embodiment, since the first connection line CNL 1  contacts both the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b,  the size of the second contact hole CH 2  may be greater than the size of other contact holes. As such, the width and/or the area of the first connection line CNL 1  may be increased. 
     When the width and/or the area of the first connection line CNL 1  is increased, the contact area of the first connection line CNL 1 , the third-b drain electrode DE 3   b,  and the fourth-b source electrode SE 4   b  may be sufficiently secured. In this case, poor contact between the third transistor T 3  and the fourth transistor T 4  may be minimized, so that the pixel PXL may display an image with a desired luminance. 
     In an exemplary embodiment, the second contact portion CNP 2  may refer to a region where the sixth drain electrode DE 6  doped with the p-type impurity contacts the seventh source electrode SE 7  doped with the n-type impurity. At this time, the sixth drain electrode DE 6  and the seventh source electrode SE 7  may be provided in the same layer on the same plane, but the inventive concepts are not limited thereto. 
     The second connection line CNL 2  may be disposed on the the second contact portion CNP 2 . The second connection line CNL 2  may contact the sixth drain electrode DE 6  and the seventh source electrode SE 7  through the seventh contact hole CH 7 . 
     More specifically, one side of the lower surface of the second connection line CNL 2  may contact the seventh source electrode SE 7 , and the other side of the lower surface of the second connection line CNL 2  may contact the sixth drain electrode DE 6 . 
     In an exemplary embodiment, since the second connection line CNL 2  contacts both the seventh source electrode SE 7  and the sixth drain electrode DE 6 , the size of the seventh contact hole CH 7  may be greater than the size of other contact holes. As such, the width and/or the area of the second connection line CNL 2  may be increased. When the width and/or the area of the second connection line CNL 2  is increased, the contact area of the second connection line CNL 2 , the seventh source electrode SE 7 , and the sixth drain electrode DE 6  may be sufficiently secured. In this case, poor contact between the sixth transistor T 6  and the seventh transistor T 7  may be minimized, so that the pixel PXL may display an image with a desired luminance. 
     Hereinafter, a structure of a display device according to an exemplary embodiment will be described with reference to  FIGS. 5 to 7 . 
     A buffer layer BFL may be provided on the substrate SUB. The buffer layer BFL may prevent the impurity from diffusing into the first to seventh transistors T 1  to T 7 . The buffer layer BFL may be provided as a single layer, or may be provided as multiple layers having at least two or more layers. When the buffer layer BFL is formed of multiple layers, each layer may be formed of the same material or may be formed of different materials. The buffer layer BFL may be omitted according to a material of the substrate SUB and a process condition. 
     A first to the seventh active patterns ACT 1  to ACT 7  may be provided on the substrate SUB. The first to the seventh active patterns ACT 1  to ACT 7  may be formed of a semiconductor material. 
     A first gate insulation layer GI may be provided on the substrate SUB on which the first to the seventh active patterns ACT 1  to ACT 7  are provided. The first gate insulation layer GI may be an inorganic insulation layer including an inorganic material. For example, the first gate insulation layer GI may include at least one of silicon nitride, silicon oxide, and silicon oxynitride. 
     The i−1 th  scan line Si−1, the i th  first scan line Sia, the i th  second scan line Sib, the emission control line Ei, and the first to seventh gate electrodes GE 1  to GE 7  may be provided on the first gate insulation layer GI. 
     The first gate electrode GE 1  may be the lower electrode LE of the storage capacitor Cst. The second gate electrode GE 2  and the third gate electrode GE 3  may be formed integrally with the i th  first scan line Sia. Since the third gate electrode GE 3  includes the third-a gate electrode GE 3   a  and the third-b gate electrode GE 3   b,  the third-a gate electrode GE 3   a  and the third-b gate electrode GE 3   b  may be formed integrally with the i th  first scan line Sia. 
     The fourth gate electrode GE 4  may be formed integrally with the i−1 th  scan line Si−1. Since the fourth gate electrode GE 4  includes the fourth-a gate electrode GE 4   a  and the fourth-b gate electrode GE 4   b,  the fourth-a gate electrode GE 4   a  and the fourth-b gate electrode GE 4   b  may be formed integrally with the i−1 th  scan line Si−1. 
     The seventh gate electrode GE 7  may be formed integrally with the i th  second scan line Sib. The fifth gate electrode GE 5  and the sixth gate electrode GE 6  may be formed integrally with the emission control line Ei. A second gate insulation layer GI 2  may be provided on the substrate SUB, on which the scan lines Si−1, Sia, and Sib are provided. 
     The upper electrode UE of the storage capacitor Cst and the initialization power supply line IPL may be provided on the second gate insulation layer GI 2 . The upper electrode UE may cover the lower electrode LE. The upper electrode UE may form the storage capacitor Cst together with the lower electrode LE with the second gate insulation layer GI 2  interposed therebetween. 
     The first interlayer insulation layer ILD 1  may be provided on the substrate SUB, on which the upper electrode UE and the initialization power supply line IPL are disposed. 
     The first and second connection lines CNL 1  and CNL 2 , the auxiliary connection line AUX, the data line Dj, and the power supply line PL may be provided on the first interlayer insulation layer ILD 1 . 
     The first connection line CNL 1  may be connected to the first gate electrode GE 1  through the first contact hole CH 1  sequentially passing through the first interlayer insulation layer ILD 1  and the second gate insulation layer GI 2 . In addition, the first connection line CNL 1  may be connected to the third-b drain electrode DE 3   b  and the fourth-b source electrode DE 4   b  through the second contact hole CH 2  sequentially passing through the first and second gate insulation layers GI 1  and GI 2 , and the first interlayer insulation layers ILD 1 . At this time, the size of the second contact hole CH 2  may be greater than the size of the first contact hole CH 1 . 
     The second connection line CNL 2  may be a pattern provided as a medium connecting the sixth drain electrode DE 6  and the first electrode AD between the sixth drain electrode DE 6  and the first electrode AD. The second connection line CNL 2  may be connected to the sixth drain electrode DE 6  and the seventh source electrode SE 7  through the seventh contact hole CH 7  sequentially passing through the first and second gate insulation layers GI 1  and GI 2 , and the first interlayer insulation layer ILD 1 . At this time, the size of the seventh contact hole CH 7  may be greater than the size of the first contact hole CH 1 . 
     The auxiliary connection line AUX may be connected to the initialization power supply line IPL through the eighth contact hole CH 8  passing through the first interlayer insulation layer ILD 1 . In addition, the auxiliary connection line AUX may be connected to the fourth-a drain electrode DE 4   a  and the seventh drain electrode DE 7  of the pixel PXL in the row through the ninth contact hole CH 9  sequentially passing through the first and second gate insulation layers GI 1  and GI 2 , and the first interlayer insulation layer ILD 1 . 
     The data line Dj may be connected to the second source electrode SE 2  through the sixth contact hole CH 6  sequentially passing through the first and second gate insulation layers GI 1  and GI 2 , and the first interlayer insulation layer ILD 1 . 
     The power supply line PL may be connected to the upper electrode UE through the third and fourth contact holes CH 3  and CH 4  passing through the first interlayer insulation layer ILD 1 . In addition, the power supply line PL may be connected to the fifth source electrode SE 5  through the fifth contact hole CH 5  sequentially passing through the first and second gate insulation layers GI 1  and GI 2 , and the first interlayer insulation layer ILD 1 . 
     A second interlayer insulation layer ILD 2  may be provided on the first and second connection lines CNL 1  and CNL 2 , the auxiliary connection line AUX, the data line Dj, and the power supply line PL. The second interlayer insulation layer ILD 2  may be an inorganic insulation layer including an inorganic material or an organic insulation layer including an organic material. 
     In an exemplary embodiment, the second interlayer insulation layer ILD 2  may be an organic insulation layer. The second interlayer insulation layer ILD 2  may be formed as a single layer, but the inventive concepts are not limited thereto, and may be formed of multiple layers. 
     When the second interlayer insulation layer ILD 2  is formed of multiple layers, the second interlayer insulation layer ILD 2  may have a structure in which a plurality of inorganic insulation layers or a plurality of organic insulation layers are alternately stacked. For example, the second interlayer insulation layer ILD 2  may have a structure in which the first organic insulation layer, an inorganic insulation layer, and the second organic insulation layer are sequentially stacked. 
     The bridge pattern BRP may be provided on the second interlayer insulation layer ILD 2 . The bridge pattern BRP may be connected to the second connection line CNL 2  through the tenth contact hole CH 10  passing through the second interlayer insulation layer ILD 2 . 
     A passivation layer PSV may be provided on the bridge pattern BRP. 
     The first electrode AD may be provided on the passivation layer PSV. The first electrode AD may be connected to the bridge pattern BRP through the eleventh contact hole CH 11  passing through the passivation layer PSV. 
     Since the bridge pattern BRP is connected to the second connection line CNL 2  through the tenth contact hole CH 10 , the first electrode AD may be connected to the sixth drain electrode DE 6  and the seventh source electrode SE 7  through the bridge pattern BRP and the second connection line CNL 2 . 
     A pixel definition layer PDL may be provided on the substrate SUB on which the first electrode AD is formed to define an emission region corresponding to each pixel PXL. The pixel definition layer PDL may expose the top surface of the first electrode AD and may protrude from the substrate SUB along the periphery of the pixel PXL. 
     An emission layer EML may be provided on the exposed upper surface of the first electrode AD. The second electrode CD may be provided on the emission layer EML. 
     The pixel definition layer PDL may include an organic insulation layer. For example, the pixel definition layer PDL may include at least one of polystyrene, polymethylmethacrylate (PMMA), polyacrylonitrile (PAN), polyamide (PA), polyimide(PI), polyarylether (PAE), heterocyclic polymer, parylene, epoxy, benzocyclobutene (BCB), siloxane based resin, and silane based resin. 
     The emission layer EML may be disposed on the exposed surface of the first electrode AD. The emission layer EML may have a multiple thin layer structure including at least one light generation layer. For example, the emission layer EML may include a hole injection layer for injecting holes having excellent transportability, a hole transport layer for increasing a chance of recombination of holes and electrons by blocking a movement of electrons which are not coupled in the light generating layer, the light generating layer which emits light by recombination of injected electrons and holes, a hole blocking layer for blocking a movement of holes which are not coupled in the light generating layer, an electron transport layer for smoothly transporting electrons to the light generating layer, and an electron injection layer for injecting electrons. 
     The color of light generated in the light generating layer may be one of red, green, blue, and white, but the inventive concepts are not limited thereto. For example, the color of light generated in the light generating layer of the emission layer EML may be one of magenta, cyan, and yellow. Each of the hole injection layer, the hole transport layer, the hole blocking layer, the electron transport layer, and the electron injection layer may be a common layer connected to each other in adjacent emission regions. 
     A thin film encapsulation film TFE covering the second electrode CD may be provided on the second electrode CD. The thin film encapsulation film TFE may be made of a single layer or may be made of multiple layers. The thin film encapsulation film TFE may include a plurality of insulation layers covering the light emitting device OLED. Specifically, the thin film encapsulation film TFE may include a plurality of inorganic layers and a plurality of organic layers. For example, the thin film encapsulation film TFE may have a structure in which the inorganic layer and the organic layer are alternately stacked. In addition, the thin film encapsulation film TFE may be an encapsulation substrate disposed on the light emitting device OLED and bonded to the substrate SUB by using a sealant. 
     Meanwhile, the display device according to an exemplary embodiment may further include a touch sensor provided on the thin film encapsulation film TFE. The touch sensor may be disposed on a surface in a direction to which an image of the substrate SUB is emitted to receive a user&#39;s touch input. The touch event to the display device may be recognized by using a hand of the user of the touch sensor or a separate input means. 
     The touch sensor may be driven by a mutual capacitance method. The mutual capacitance method senses a capacitance change due to an interaction between two touch sensing electrodes. In addition, the touch sensor may be driven by a self capacitance method. The self capacitance method senses a capacitance change of a sensing electrode of a touched region when a user touches the sensing electrode by using touch sensing electrodes arranged in a matrix and sensing lines connected to each of the touch sensing electrodes. 
     The touch sensor may include the touch sensing electrode, the sensing line connected to the touch sensing electrode, and a pad unit connected to an end of the sensing line. 
     A window may be provided on the touch sensor to protect the exposed surface of the touch sensor. The window transmits an image from the substrate SUB and alleviates an external impact, thereby preventing the display device from being broken or malfunctioning due to the external impact. 
       FIGS. 8 to 19  are cross-sectional views sequentially showing a manufacturing method of the display device shown in  FIG. 5 . 
     First, referring to  FIGS. 5 to 8 , a substrate SUB may be provided. 
     The substrate SUB may be formed of a transparent glass material including silicon dioxide (SiO 2 ) as a main component. The substrate SUB is not necessarily limited thereto, but may be formed of a transparent plastic material. 
     After a semiconductor material layer is deposited on the substrate SUB, a mask process is performed to form a semiconductor layer SCL. The semiconductor material layer may be formed of silicon (Si), such as amorphous silicon (a-Si) or polysilicon (p-Si). When the semiconductor material layer is formed of amorphous silicon (a-Si), a crystallization process may be further performed using a laser or the like. 
     According to an exemplary embodiment, the semiconductor material layer may be formed of a semiconductor oxide including a binary compound (ABx), a ternary compound (ABxCy), a quarternary compound (ABxCyDz), and the like and including indium(In), zinc(Zn), gallium(Ga), tin(Sn), titanium(Ti), aluminum(Al), hafnium (Hf), zirconium (Zr), magnesium(Mg), and the like. These may be used alone or in combination with each other. 
     Referring to  FIGS. 5 to 9 , a semiconductor layer SCL 1  (hereinafter, referred to as ‘first semiconductor layer’) of a P-type thin film transistor is formed by doping the semiconductor layer SCL with an impurity including boron or the like. The first semiconductor layer SCL 1  may be a semiconductor layer of each of the first to third transistors T 1  to T 3 , and the fifth and sixth transistors T 5  and T 6 . 
     Referring to  FIGS. 5 to 10 , a photoresist pattern is formed on the substrate SUB including the first semiconductor layer SCL 1 . The photoresist pattern may cover the first semiconductor layer SCL 1  and expose the semiconductor layer SCL to the outside. 
     Next, a semiconductor layer SCL 2  (hereinafter, referred to as ‘second semiconductor layer’) of an N-type thin film transistor is formed by doping the exposed semiconductor layer SCL with an impurity including boron or the like. The second semiconductor layer SCL 2  may be a semiconductor layer of each of the fourth and seventh transistors T 4  and T 7 . 
     The first semiconductor layer SCL 1  and the second semiconductor layer SCL 2  may be on the same plane and may be formed on the same layer. According to an exemplary embodiment, the boundary between the first semiconductor layer SCL 1  and the second semiconductor layer SCL 2  may not be clearly divided, or the boundary may be clearly divided. 
     Next, the photoresist pattern is removed from the substrate SUB. 
     Referring to  FIGS. 5 to 11 , a first gate insulation layer GI 1  may be formed on the first and second semiconductor layers SCL 1  and SCL 2 . The first gate insulation layer GI 1  may be an inorganic insulation layer including an inorganic material. 
     A first conductive material layer is deposited on the first gate insulation layer GI 1 , and a lower electrode LE, an emission control line Ei, an i th  first scan line Sia, and a conductive pattern CP are formed by using a mask process. Herein, the lower electrode LE may include a first gate electrode GE 1 , the emission control line Ei may include a fifth and sixth gate electrodes GE 5  and GE 6 , and the i th  first scan line Sia may include a third-a and third-b gate electrodes GE 3   a  and GE 3   b.    
     In an exemplary embodiment, the conductive pattern CP may be provided on the second semiconductor layer SCL 2  to cover the second semiconductor layer SCL 2 . 
     Referring to  FIGS. 5 to 12 , by using the lower electrode LE, the emission control line Ei, the i th  first scan line Sia, and the conductive pattern CP as a mask, the first semiconductor layer SCL 1  is doped with a high concentration p-type impurity. Herein, the p-type impurity may include aluminum, gallium, indium, boron, and the like, which have three outermost electrons. 
     At this time, the second semiconductor layer SCL 2  may be covered with the conductive pattern CP. Therefore, the p-type impurity may not be doped in the second semiconductor layer SCL 2 . 
     The first, second, third-a, third-b, fifth, and sixth source electrode SE 1 , SE 2 , SE 3   a,  SE 3   b,  SE 5 , and SE 6  having conductivity may be formed by doping the first semiconductor layer SCL 1  with a p-type impurity at high concentration. At the same time, the first, second, third-a, third-b, fifth and sixth drain electrodes DE 1 , DE 2 , DE 3   a,  DE 3   b,  DE 5 , and DE 6  may be formed. 
     Due to the first gate electrode GE 1 , the first semiconductor layer SCL 1 , may become a first active pattern ACT 1 , which is not doped with a p-type impurity at a high concentration. The first active pattern ACT 1  may be a channel of the first transistor T 1 . Therefore, the first gate electrode GE 1 , the first active pattern ACT 1 , the first source electrode SE 1 , and the first drain electrode DE 1  may constitute the first transistor T 1 , which is a P-type thin film transistor. 
     Due to the second gate electrode GE 2 , the first semiconductor layer SCL 1  may become a second active pattern ACT 2 , which is not doped with a p-type impurity at a high concentration. The second active pattern ACT 2  may be a channel of the second transistor T 2 . Therefore, the second gate electrode GE 2 , the second active pattern ACT 2 , the second source electrode SE 2 , and the second drain electrode DE 2  may constitute the second transistor T 2 , which is a P-type thin film transistor. 
     Due to the third-a gate electrode GE 3   a,  the first semiconductor layer SCL 1  may become the third-a active pattern ACT 3   a,  which is not doped with the p-type impurity at a high concentration. The third-a active pattern ACT 3   a  may be a channel of the third-3 transistor T 3   a.  Therefore, the third-a gate electrode GE 3   a,  the third active pattern ACT 3   a,  the third-a source electrode SE 3   a,  and the third-a drain electrode DE 3   a  may constitute the third-a transistor T 3   a,  which is a P-type thin film transistor. 
     Due to the third-b gate electrode GE 3   b,  the first semiconductor layer SCL 1  may become the third-b active pattern ACT 3   b,  which is not doped with a p-type impurity at a high concentration. The third-b active pattern ACT 3   b  may be a channel of the third transistor T 3   b.  Therefore, the third-b gate electrode GE 3   b,  the third-b active pattern ACT 3   b,  the third-b source electrode SE 3   b,  and the third-b drain electrode DE 3   b  may constitute the third-b transistor T 3   b,  which is a P-type thin film transistor. 
     Due to the fifth gate electrode GE 5 , the first semiconductor layer SCL 1 , may become the fifth active pattern ACT 5  which is not doped with a p-type impurity at a high concentration. The fifth active pattern ACT 5  may be a channel of the fifth transistor T 5 . Therefore, the fifth gate electrode GE 5 , the fifth active pattern ACT 5 , the fifth source electrode SE 5 , and the fifth drain electrode DE 5  may constitute the fifth transistor T 5 , which is a P-type thin film transistor. 
     Due to the sixth gate electrode GE 6 , the first semiconductor layer SCL 1  may become the sixth active pattern ACT 6 , which is not doped with a p-type impurity at a high concentration,. The sixth active pattern ACT 6  may be a channel of the sixth transistor T 6 . Therefore, the sixth gate electrode GE 6 , the sixth active pattern ACT 6 , the sixth source electrode SE 6 , and the sixth drain electrode DE 6  may constitute the sixth transistor T 6 , which is a P-type thin film transistor. 
     Referring to  FIGS. 5 to 13 , a photoresist pattern is formed on the substrate SUB on which the emission control line Ei is formed. 
     The photoresist pattern may cover the first to third transistors T 1  to T 3 , the fifth and sixth transistors T 5  and T 6 , the emission control line Ei, and the i th  first scan line Sia, and may partially expose the conductive pattern CP. 
     Next, a mask process is performed to pattern the conductive pattern CP, thereby forming the i−1 th  scan line Si−1 and the i th  second scan line Sib. The i−1 th  scan line Si−1 may include the fourth-a and fourth-b gate electrodes GE 4   a  and GE 4   b,  and the i th  second scan line Sib may include a seventh gate electrode GE 7 . 
     Next, the second semiconductor layer SCL 2  is doped with an n-type impurity at a high concentration by using the i−1 th  scan line Si−1 and the i th  second scan line Sib as a mask. Herein, the n-type impurity may include phosphorus, arsenic, antimony, and the like, which have five outermost electrons. 
     At this time, the first to third transistors T 1  to T 3  and the fifth and sixth transistors T 5  and T 6  may be covered by the photoresist pattern. Therefore, the semiconductor layers of each of the first to third transistors T 1  to T 3  and the fifth and fifth transistors T 5  and T 6  may not be doped with the n-type impurity. 
     Since the second semiconductor layer SCL 2  is doped with the n-type impurity at a high concentration, the fourth-a, fourth-b, and seventh source electrodes SE 4   a,  SE 4   b,  and SE 7  having conductivity may be formed, and at the same time, the fourth-a, fourth-b, and seventh drain electrodes DE 4   a,  DE 4   b,  and DE 7  may be formed. 
     Due to the fourth-a gate electrode GE 4   a,  the second semiconductor layer SCL 2  may become the fourth-a active pattern ACT 4   a,  which is not doped with the n-type impurity at a high concentration. The fourth-a active pattern ACT 4   a  may be a channel of the fourth-a transistor T 4   a.  Therefore, the fourth-a gate electrode GE 4   a,  the fourth-a active pattern ACT 4   a,  the fourth-a source electrode SE 4   a,  and the fourth-a drain electrode DE 4   a  may constitute the fourth-a transistor T 4   a,  which is an N-type thin film transistor. 
     Due to the fourth-b gate electrode GE 4   b,  the second semiconductor layer SCL 2  may become the fourth-b active pattern ACT 4   b,  which is not doped with the n-type impurity at a high concentration. The fourth-b active pattern ACT 4   b  may be a channel of the fourth-b transistor T 4   b.  Therefore, the fourth-b gate electrode GE 4   b,  the fourth-b active pattern ACT 4   b,  the fourth-b source electrode SE 4   b,  and the fourth-b drain electrode DE 4   b  may constitute the fourth-b transistor T 4   b,  which is an N-type thin film transistor. 
     Due to the seventh gate electrode GE 7 , the second semiconductor layer SCL 2  may become the seventh active pattern ACT 7 , which is not doped with the n-type impurity at a high concentration. The seventh active pattern ACT 7  may be a channel of the seventh transistor T 7 . Therefore, the seventh gate electrode GE 7 , the seventh active pattern ACT 7 , the seventh source electrode SE 7 , and the seventh drain electrode DE 7  may constitute the seventh transistor T 7 , which is an N-type thin film transistor. 
     Herein, the sixth drain electrode DE 6  and the seventh source electrode SE 7 , which are doped with different impurities, may be adjacent to each other. In addition, the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b,  which are doped with different impurities, may be adjacent to each other. 
     After injecting the n-type impurity, the photoresist pattern on the substrate SUB is removed. 
     Referring to  FIGS. 5 to 14 , a second gate insulating layer GI 2  may be formed on the substrate SUB on which the seventh transistor T 7  and the like are formed. The second gate insulation layer GI 2  may be an inorganic insulation layer including an inorganic material. 
     After a second conductive material layer is deposited on the second gate insulation layer GI 2 , a masking process may be performed to form an initialization power supply line IPL and an upper electrode UE. 
     Referring to  FIGS. 5 to 15 , after an insulation material layer may be deposited on the substrate SUB on which the upper electrode UE is formed, a masking process may be performed to form a first interlayer insulation layer ILD 1 . 
     The first interlayer insulation layer ILD 1  may include an eighth contact hole CH 8  exposing a portion of the initialization power supply line IPL 1 . In addition, the first interlayer insulation layer ILD 1  may include a seventh contact hole CH 7  exposing the seventh source electrode SE 7  and the sixth drain electrode DE 6  adjacent to each other. 
     In addition, the first interlayer insulation layer ILD 1  may include the second contact hole CH 2  exposing the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  adjacent to each other. 
     Subsequently, after a third conductive material layer is deposited on the first interlayer insulation layer ILD 1 , a mask process may be performed to form a first and second connection lines CNL 1  and CNL 2 , a power supply line PL, an auxiliary connection line AUX, and a data line Dj. 
     The first connection line CNL 1  may contact the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  doped with different impurities through the second contact hole CH 2 . The second connection line CNL 2  may contact the sixth drain electrode DE 6  and the seventh source electrode SE 7  doped with different impurities through the seventh contact hole CH 7 . The auxiliary connection line AUX may contact the initialization power supply line IPL through the eighth contact hole CH 8 . 
     Referring to  FIGS. 5 to 16 , after an insulation material layer is deposited on the substrate SUB on which the first and second connection lines CNL 1  and CNL 2  are formed, a mask process may be performed to form the second interlayer insulation layer ILD 2 . The second interlayer insulation layer ILD 2  may include a tenth contact hole CH 10  exposing a portion of the second connection line CNL 2 . 
     Next, after a fourth conductive material layer is deposited on the second interlayer insulation layer ILD 2 , a mask process may be performed to form a bridge pattern BRP. The bridge pattern BRP may contact the second connection line CNL 2  through the tenth contact hole CH 10 . 
     Referring to  FIGS. 5 to 17 , after an insulation material layer may be deposited on the substrate SUB on which the bridge pattern BRP is formed, a mask process may be performed to form a passivation layer PSV. The passivation layer PSV may include an eleventh contact hole CH 11  exposing a portion of the bridge pattern BRP. 
     Next, after a fifth conductive material layer is deposited on the passivation layer PSV, a mask process may be performed to form the first electrode AD. The first electrode AD may be connected to the second connection line CNL 2  through the eleventh contact hole CH 11 . 
     Referring to  FIGS. 5 to 18 , a pixel definition layer PDL including an opening exposing a portion of the first electrode AD may be formed on the first electrode AD. Next, an emission layer EML may be formed on a surface of the first electrode AD exposed by the pixel definition layer PDL. A second electrode CD may be formed on the emission layer EML. The first electrode AD, the emission layer EML, and the second electrode CD may constitute a light emitting device OLED. 
     Referring to  FIGS. 5 to 19 , a thin film encapsulation film TFE may be formed on the substrate SUB on which the light emitting device OLED is formed. 
       FIG. 20A  is an enlarged cross-sectional view of the region EA 1  of  FIG. 6  according to an exemplary embodiment.  FIGS. 20B and 20C  are cross-sectional views of the region EA 1  of  FIG. 6  according to exemplary embodiments. 
     Referring to  FIGS. 6, 20A, 20B, and 20C , the first connection line CNL 1  may contact the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  through the second contact hole CH 2  at the first contact CNP 1 . 
     Specifically, one side of the lower surface of the first connection line CNL 1  may contact the third-b drain electrode DE 3   b,  and the other side of the lower surface of the first connection line CNL 1  may contact the fourth-b source electrode SE 4   b.    
     As shown in  FIG. 20A , the third-b drain electrode DE 3   b  doped with the p-type impurity at high concentration and the fourth-b source electrode SE 4   b  doped with the n-type impurity at high concentration may be provided adjacent to each other on the substrate SUB. More particularly, within the first contact portion CNP 1 , the fourth-b source electrode SE 4   b  may be provided directly on the left side of the third-b drain electrode DE 3   b.    
     According to an exemplary embodiment, due to misalignment that may be occurred during the manufacturing process, an overlapping portion OL, in which a region doped with the p-type impurity and a region doped with the n-type impurity are overlapped, may be provided on the first contact portion CNP 1  as shown in  FIG. 20B . 
     In this case, one side of the lower surface of the first connection line CNL 1  may contact the third-b drain electrode DE 3   b,  the other side of the lower surface of the first connection line CNL 1  may contact the fourth-b source electrode SE 4   b,  and the center of the first connection line CNL 1  between the two sides of the lower surface of the first connection line CNL 1  may contact the overlapping portion OL. 
     The overlapping portion OL may be an electrically neutral region, in which the p-type impurity and the n-type impurity are doped. Therefore, the overlapping portion OL may not affect the electrical connection of the first connection line CNL 1  to the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b.    
     In addition, according to an exemplary embodiment, due to misalignment that may be occurred during the manufacturing process, an undoped region, in which the p-type impurity and the n-type impurity are not doped, may be provided at the first contact portion CNP 1  as shown in  FIG. 20C . The undoped region may be a non-overlapping portion NOL in which the p-type impurity and the n-type impurity are not overlapped. 
     In this case, one side of the lower surface of the first connection line CNL 1  may contact the third-b drain electrode DE 3   b,  the other side of the lower surface of the first connection line CNL 1  may contact the fourth-b source electrode SE 4   b,  and the center of the first connection line CNL 1  between the two sides of the lower surface of the first connection line CNL 1  may contact the non-overlapping portion NOL. More particularly, the first connection line CNL 1  may contact the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  with the non-overlapping portion NOL interposed therebetween. 
     The non-overlapping portion NOL may be an electrically neutral region, in which the p-type impurity and the n-type impurity are not doped. Therefore, the non-overlapping portion NOL may not affect the electrical connection of the first connection line CNL 1  to the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b.    
     Meanwhile, the second contact hole CH 2  may be formed to have at least a predetermined width so that the first connection line CNL 1  may stably contact the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b.    
     The second contact hole CH 2  may be formed to have at least a predetermined width in consideration of cases when the first connection line CNL 1  contacts only the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b,  when the first connection line CNL 1  also contacts the overlapping portion OL, and when the second connection line CNL 1  also contacts the non-overlapping portion NOL. 
     In addition, when determining a predetermined width of the second contact hole CH 2 , it can also be taken into account that the second contact hole CH 2  may be biased by the third-b drain electrode DE 3   b  or by the fourth-b source electrode SE 4   b  during manufacturing problems. 
     According to an exemplary embodiment, the width “d” of the second contact hole CH 2  may be about 0.2 μm to 3 μm, but the inventive concepts are not limited thereto. 
     As described above, since the second contact hole CH 2  is formed to have at least a predetermined width, the size of the second contact hole CH 2  may be greater than other contact holes, for example, the first contact hole CH 1 . Thus, the width and/or the area of the first connection line CNL 1  may be increased. When the width and/or the area of the first connection line CNL 1  becomes large, the contact areas of the first connection line CNL 1 , the third-b drain electrode DE 3   b,  and the fourth-b source electrode SE 4   b  may be sufficiently secured. 
     In an exemplary embodiment, since the seventh contact hole CH 7  may be formed in substantially the same method as that forming the second contact hole CH 2 , detailed descriptions thereof will be omitted to avoid redundancy. 
     Hereinafter, a current characteristic of a pixel according to an exemplary embodiment will be described with reference to  FIGS. 21A and 21B . 
       FIGS. 21A and 21B  are graphs showing current characteristics of a conventional pixel and a pixel according to an exemplary embodiment. In  FIG. 21A , Comparative Example shows current characteristics of conventional pixels including seven P-type thin film transistors, and Example shows current characteristics of a pixel according to an exemplary embodiment. 
     Referring to  FIG. 21B , it can be confirmed that a current deviation according to a rated current in Example is similar to a current deviation according to a rated current in Comparative Example. Therefore, it can be confirmed that even though Example include different type of thin film transistors, Example can have similar current characteristics to current characteristics in pixels including the same type of thin film transistors. 
       FIG. 22  is an enlarged plan view of two pixels included in the display device according to another exemplary, and  FIG. 23  is a cross-sectional view taken along line III-III′ of  FIG. 22 . In order to avoid redundancy, differences from the above-described exemplary embodiment will be mainly described. Detailed descriptions of the elements that are substantially the same as those already described above will be omitted to avoid redundancy s. 
     Referring to  FIG. 22 , k th  and k+1 th  pixels PXL_K and PXL_K+1 are arranged in the i th  pixel row arranged in the display region of  FIG. 22 , and three scan lines Si−1, Sia and Sib, one emission control line Ei, two data lines Dj and Dj+1, two power supply lines PL 1  and PL 2 , and one initialization power supply line IPL, which are connected to the k th  and k+1 th  pixels PXL_K and PXL_K+1 are disposed. 
     Each of the k th  and k+1 th  pixels PXL_K and PXL_K+1 shown in  FIGS. 22 and 23  may have substantially the same or similar configuration as the pixels of  FIGS. 5 and 6 , except that the semiconductor layers of the fourth and seventh transistors T 4  and T 7  are disposed in a different layer from the semiconductor layers of the first to third transistors T 1  to T 3  and the fifth and sixth transistors T 5  and T 6 . 
     Referring to  FIGS. 22 and 23 , a display device according to another exemplary embodiment may include a substrate SUB and the k th  and k+1 th  pixels PXL_K and PXL_K+1 provided on the substrate SUB. 
     Each of the k th  and k+1 th  pixels PXL_K and PXL_K+1 may include a light emitting device (see OLED in  FIG. 3 ) and a pixel circuit (see PC in  FIG. 3 ) for driving the light emitting device OLED. Herein, the pixel circuit PC may include first to seventh transistors T 1  to T 7 , and a storage capacitor Cst. 
     The fourth transistor T 4  and the seventh transistor T 7 , among the first to seventh transistors T 1  to T 7 , may be set as an N-type thin film transistor including a semiconductor layer doped with an n-type impurity. The other transistors, for example, the first to third transistors T 1  to T 3 , and the fifth and sixth transistors T 5  and T 6  may be set as a P-type thin film transistor including a semiconductor layer doped with a p-type impurity. 
     In an exemplary embodiment, the semiconductor layer doped with the p-type impurity and the semiconductor layer doped with the n-type impurity may be disposed in different layers from each other. For example, the semiconductor layer doped with the n-type impurity may be provided on the semiconductor layer doped with the p-type impurity, or vice versa, but the inventive concepts are not limited thereto. 
     The semiconductor layer included in each of the first to third transistors T 1  to T 3  and the fifth and sixth transistors T 5  and T 6 , which are set to the P-type thin film transistor, may be disposed on a different layer from the semiconductor layer included in each of the fourth and seventh transistors T 4 . 
     Herein, the semiconductor layer may include an active pattern, and source and drain electrodes connected to the active pattern, respectively. 
     Each of the k th  and k+1 th  pixels PXL_K and PXL_K+1 may include first and second contact portions CNP 1  and CNP 2 , to which different types of thin film transistors are in contact thereto. 
     The first contact portion CNP 1  may be disposed between the third-b transistor T 3   b  formed of the P-type thin film transistor and the fourth-b transistor T 4   b  formed of the N-type thin film transistor. 
     More particularly, the first contact portion CNP 1  may refer to a region where the third-b drain electrode DE 3   b  of the third-b transistor T 3   b  doped with the p-type impurity and the fourth-b source electrode SE 4   b  of the fourth-b transistor T 4   b  doped with the n-type impurity are in contact with each other. 
     The third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  may be in contact with the first connection line CNL 1  at the first contact portion CNP 1 . 
     In an exemplary embodiment, the semiconductor layer of the third transistor T 3  formed of the P-type thin film transistor and the semiconductor layer of the fourth transistor T 4  formed of the N-type thin film transistor may be provided at a different layer from each other. Therefore, the third-b drain electrode DE 3   b  and the fourth-b source electrode SE 4   b  may be provided at a different layer from each other. 
     More specifically, the fourth-b source electrode SE 4   b  may be provided on the third-b drain electrode DE 3   b  with a buffer layer BFL interposed therebetween. Herein, the buffer layer BFL may be provided on the substrate SUB to provide a flat surface (or planarize) on the substrate SUB and to prevent penetration of impurities. 
     The third-b drain electrode DE 3   b  may be connected to one side of the first connection line CNL 1  through a second- 1  contact hole CH 2 _ 1  sequentially passing through the first interlayer insulation layer ILD 1 , the second gate insulation layer GI 2 , the first gate insulation layer GI 1 , and the buffer layer BFL. 
     The fourth-b source electrode SE 4   b  may be connected to the other side of the first connection line CNL 1  through a second-2 contact hole CH 2 _ 2  sequentially passing through the first interlayer insulation layer ILD 1 , the second gate insulation layer GI 2 , and the first gate insulation layer GI 1 . As a result, the third-b drain electrode DE 3   b  may be connected to the fourth-b source electrode SE 4   b  through the second-1 and second-2 contact holes CH 2 _ 1  and CH 2 _ 2  and the first connection line CNL 1 . 
     The second contact portion CNP 2  may be disposed between the sixth transistor T 6  formed of the P-type thin film transistor and the seventh transistor T 7  formed of the N-type thin film transistor. More particularly, the second contact portion CNP 2  may refer to a region where the sixth drain electrode DE 6  of the sixth transistor T 6  doped with the p-type impurity and the seventh source electrode SE 7  of the seventh transistor T 7  doped with the n-type impurity are in contact with each other. 
     The sixth drain electrode DE 6  and the seventh source electrode SE 7  may be in contact with the second connection line CNL 2  at the second contact portion CNP 2 . 
     In an exemplary embodiment, the semiconductor layer of the sixth transistor T 6  formed of the P-type thin film transistor and the semiconductor layer of the seventh transistor T 7  formed of the N-type thin film transistor may be provided at a different layer from each other. Therefore, the sixth drain electrode DE 6  and the seventh source electrode SE 7  may be provided at a different layer from each other. More specifically, the seventh source electrode SE 7  may be provided on the sixth drain electrode DE 6  with the buffer layer BFL interposed therebetween. 
     The sixth drain electrode DE 6  may be connected to one side of the second connection line CNL 2  through a seventh-2 contact hole CH 7 _ 2  sequentially passing through the first interlayer insulation layer ILD 1 , the second gate insulation layer GI 2 , the first gate insulation layer GI 1 , and the buffer layer BFL. 
     The seventh source electrode SE 7  may be connected to the other side of the second connection line CNL 2  through the seventh-1 contact hole CH 7 _ 1  sequentially passing through the first interlayer insulation layer ILD 1 , the second gate insulation layer GI 2 , and the first gate insulation layer GI 1 . As a result, the sixth drain electrode DE 6  may be connected to the seventh source electrode SE 7  through the seventh-1 and seventh-2 contact holes CH 7 _ 1  and CH 7 _ 2  and the second connection line CNL 2 . 
     A display device according to an exemplary embodiment may be applied to various electronic devices. For example, the display device may be applied to a television, a notebook, a mobile phone, a smart phone, a smart pad, a PMP, a PDA, a navigation device, various wearable devices such as a smart watch, and the like. 
     According to an exemplary embodiment, a pixel of a display device may have reduced defects. 
     Although certain exemplary embodiments and implementations have been described herein, other embodiments and modifications will be apparent from this description. Accordingly, the inventive concepts are not limited to such embodiments, but rather to the broader scope of the appended claims and various obvious modifications and equivalent arrangements as would be apparent to a person of ordinary skill in the art.