Patent Publication Number: US-2009237609-A1

Title: Display Device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2008-0025936 filed in the Korean Intellectual Property Office on Mar. 20, 2008, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Technical Field 
     The present invention relates to a display device, and more particularly, the present invention relates to the display device using a soda lime glass substrate. 
     (b) Description of the Related Art 
     Recently, flat panel display devices have gained acceptance in the market place. A flat panel display is a display device with a small thickness relative to the size of the screen. Examples of flat panel displays include liquid crystal displays (LCD), plasma display panels (PDP), organic light emitting devices (OLED), and electrophoretic displays (EPD). 
     The liquid crystal display (LCD) is the most commonly used flat panel display device. The LCD includes two substrates with electrodes formed thereon and a liquid crystal layer interposed between the two substrates. In the LCD, a voltage is applied to the electrodes to rearrange liquid crystal molecules of the liquid crystal layer to thereby control the transmittance of light passing through the liquid crystal layer. The PDP is a display device for displaying images by using plasma generated by gas discharge. The electrophoretic display is a display device utilizing the electrophoretic phenomenon to repeatedly write or erase information made of symbols such as characters and numbers. In the OLED, electrons and holes are injected into an organic illumination layer respectively from a cathode (electron injection electrode) and an anode (hole injection electrode). The injected electrons and holes are combined to generate excitons, which illuminate when converting from an excited state to a ground state. The organic light emitting display is remarkably thin and surpasses the liquid crystal display in terms of display quality, high response speed, and contrast ratio. Accordingly, the organic light emitting display is often spotlighted as a next-generation display device. 
     These display devices generally include an insulating substrate and a plurality of thin film elements formed thereon. The insulating substrate may be made of a transparent material such as glass. A glass substrate may be a non-alkali-containing glass substrate that does not contain an alkali component or an alkali-containing glass substrate that contains an alkali component. 
     SUMMARY OF THE INVENTION 
     A non-alkali-containing glass substrate has a high melting point of 1700° C. Non-alkali-containing glass substrates may be manufactured by a fusion process and in this process, lateral sides of the glass are cooled by air. The fusion process used to manufacture these substrates may be expensive. Since an alkali-containing glass substrate can be manufactured at a relative low melting temperature, the manufacturing cost can be reduced compared to the non-alkali-containing glass substrate. However, an alkali component contained in the alkali-containing substrate may be prone to melting during follow-up processes, thereby affecting stability of thin film elements thereof. 
     Exemplary embodiments of the present invention seek to reduce the cost of manufacturing alkali-containing substrates used in flat panels while obtaining stable thin film elements. 
     A display device according to an exemplary embodiment of the present invention includes an alkali-containing glass substrate, a transparent organic layer contacting the glass substrate, and a plurality of thin film elements formed on the transparent organic layer. 
     The glass substrate may be a soda lime glass substrate. The transparent organic layer may have a same transparency as the glass substrate and a refractive index in a range of about 1.5 to about 1.6. The transparent organic layer may have a glass transition temperature of about 250° C. to about 450° C. The transparent organic layer may be made of polyimide. The thickness of the transparent organic layer may be in a range of about 0.3 μm to 50 μm. The sheet resistance of the transparent organic layer may be less than 2×10 17  Ωcm. The thin film elements may include a thin film transistor. The thin film elements may further include an organic light emitting element. 
     The display device may further include a liquid crystal layer formed on the thin film elements. The display device may further include an electrophoretic active layer formed on the thin film elements. The thin film elements may include a color filter. 
     A liquid crystal display device according to another exemplary embodiment of the present invention includes a first panel including a first substrate having pixel electrodes, thin film transistors and signal lines thereon, a second panel including a second substrate having a common electrode, at least one color filter, and at least one light blocking member, and a liquid crystal layer disposed between the first panel and the second panel, wherein at least one of the first and the second substrates is an alkali-containing glass substrate, and the at least one alkali-containing glass substrate has a transparent organic layer contacting therewith. 
     The alkali-containing glass substrate is a soda lime glass substrate. The transparent organic layer has a same transparency as the alkali-containing glass substrate and a refractive index in a range of about 1.5 to about 1.6. The transparent organic layer has a glass transition temperature of about 250° C. to about 450° C. The organic layer includes polyimide. The thickness of the transparent organic layer is in a range of about 0.3 μm to about 50 μm. The sheet resistance of the organic layer is less than about 2×10 17  Ωcm. 
     An organic light emitting device according to another exemplary embodiment of the present invention includes a first substrate including alkali-containing glass, and a transparent organic layer including polyimide formed on the substrate, wherein the transparent organic layer has the same transparency as the first substrate, and a refractive index in a range of about 1.5 to about 1.6. 
     The transparent organic layer has a glass transition temperature T g  of about 250° C. to about 450° C. The thickness of the organic layer is in a range of about 0.3 μm to about 50 μm. The sheet resistance of the transparent organic layer is in a range of about 1×10 17  Ωcm to about 2×10 17  Ωcm. 
     According to an exemplary embodiment of the present invention, the substrate of the display device uses an inexpensive alkali-containing glass substrate such that the manufacturing cost of the display device may be reduced. Also, transparent polyimide is formed on the alkali-containing glass substrate such that the manufacturing defect rate of the thin film elements may be reduced. Furthermore, the transparent polyimide is used as an alignment material in the manufacturing process of the display device such that the process for forming it on the alkali-containing glass substrate may be simply and easily executed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and aspects of the exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a liquid crystal display according to an exemplary embodiment of the present invention; 
         FIG. 2  is a cross-sectional view of the liquid crystal display shown in  FIG. 1  taken along the line II-II; 
         FIG. 3  is a layout view of an organic light emitting device according to an exemplary embodiment of the present invention; 
         FIG. 4  is a cross-sectional view of the organic light emitting device shown in  FIG. 3  taken along the line IV-IV; 
         FIG. 5  is a cross-sectional view of an electrophoretic display according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a graph showing an operation result of the thin film transistor according to existence and nonexistence of a transparent organic layer on a substrate. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Exemplary embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings. As those skilled in the art would realize, the described exemplary embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
     In the drawings, the thickness of layers, films, panels, regions, etc., may be exaggerated for clarity. Like reference numerals may designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. 
     A liquid crystal display according to an exemplary embodiment of the present invention will be described in detail with reference to  FIG. 1  and  FIG. 2 . 
       FIG. 1  is a perspective view of a liquid crystal display according to an exemplary embodiment of the present invention, and  FIG. 2  is a cross-sectional view of the liquid crystal display shown in  FIG. 1  taken along the line II-II. 
     Referring to  FIG. 1 , a liquid crystal display includes a lower panel  100 , an upper panel  200 , and a liquid crystal layer  3  formed between the lower panel  100  and the upper panel  200 . 
     The lower panel  100  includes a substrate and a plurality of thin film elements formed thereon. The substrate is made of soda lime glass. The thin film elements include transparent organic layers, pixel electrodes, thin film transistors, and various signal lines. 
     The upper panel  200  faces the lower panel  100 , and is smaller than the lower panel  100  such that a portion of the edge of the lower panel  100  is not covered by the upper panel  200  and is exposed by the upper panel  200 . The upper panel  200  includes a substrate and a plurality of thin film elements. The substrate is made of soda lime glass. The thin film elements include a transparent organic layer, a common electrode, color filters, and a light blocking member. 
     The liquid crystal display also includes flexible printed circuit films  410  and  510 , IC chips  430  and  530 , printed circuit boards (PCBs)  450  and  550 , and conductive adhesives  470  and  570 . 
     One end of each of the flexible printed circuit films  410  and  510  is attached to the exposed edge of the lower panel  100  through the conductive adhesives  470  and  570 , and the other ends thereof are attached to the printed circuit boards (PCB)  450  and  550  as a signal supply through the conductive adhesives  470  and  570 , respectively. The IC chip  430  and  530  (TCP type) are formed on the flexible printed circuit films  410  and  510 . The flexible printed circuit films  410  and  510  may be bent, and the printed circuit boards (PCB)  450  and  550  are disposed under the lower panel  100  (a bent TCP). Alternatively, the flexible printed circuit films  410  and  510  may be straight, and may be disposed in parallel (a flat TCP). The IC chips  430  and  530  may be directly mounted on the lower panel  100  (COG/FOG type). 
     A lighting unit  80  is disposed under the lower panel  100 , and a cover  60  is disposed on the upper panel  200 . The lower panel  100  and the upper panel  200  may be stably fixed to the lighting unit  80  through the cover  60 . 
     A detailed structure of the lower panel  100  and the upper panel  200  will be described with reference to  FIG. 2 . 
     A transparent organic layer  115  is formed on a lower substrate  110 . The lower substrate  110  is made of an inexpensive soda lime glass. The transparent organic layer  115  is made of a polyimide, and contacts the lower substrate  110 . The transparent organic layer  115  may have the same transparency as the glass of the display panels  100  and  200 . The transparent organic layer  115  may have a transition temperature T g  of about 250° C. to about 450° C. Accordingly, the transparent organic layer  115  may be used in the high temperature process. The thermal expansion coefficient of the glass is in a range of about 3 ppm to about 80 ppm. The refractive index of the transparent organic layer  115  is in a range of about 1.5 to about 1.6, the sheet resistance thereof is in a range of about 1×10 17  Ωcm to about 2×10 17  Ωcm, the dielectric constant thereof is in a range of about 2.5 MHz to about 3.5 MHz, and the Young&#39;s modulus thereof is in a range of about 1.5 GPa to about 5 GPa. In general, an organic layer made of a polyimide may have a glass transition temperature of about 350° C. to about 550° C. 
     The transparent organic layer  115  may be formed on the lower substrate  110  through spin coating, slit coating, spin and slit coating, slot dying, or gravure printing, and may be hardened in a range of temperatures form about 150° C. to about 250° C. In this way, the transparent organic layer  115  may completely cover impurities that exist on the lower substrate  110 . Accordingly, the impurities and the alkali components that exist in the lower substrate  110  do not influence the thin film elements. 
     The thickness t of the transparent organic layer  115  may be in a range of about 0.3 μm to about 50 μm. When the thickness t of the transparent organic layer  115  is less than about 0.3 μm, it is difficult to uniformly form the transparent organic layer  115  on the lower substrate  110 , and the transparent organic layer  115  may not cover the impurities on the lower substrate  110  such that many defects may be generated during the manufacture of the display device. When the thickness t of the transparent organic layer  115  is more than about 50 μm, the transmittance is reduced and the transparent organic layer  115  may be bent during hardening. Furthermore, it is difficult to thickly form the transparent organic layer  115 , and when the thickness is increased, further advantageous effects are not generated. 
     A gate conductor including a plurality of gate lines (not shown) and a plurality of storage electrodes  133  are formed on the transparent organic layer  115 . The gate lines transmit gate signals and include a plurality of gate electrodes  124  and end portions (not shown) having a wide area for connection with a different layer or the IC chip  430 . The storage electrodes  133  are separated from the gate lines. 
     A gate insulating layer  140 , a plurality of semiconductors  154 , a plurality of ohmic contacts  163  and  165 , a plurality of data lines  171 , and a plurality of drain electrodes  175  are sequentially formed on the gate conductor. 
     The data lines  171  transmit data signals, and include a plurality of source electrodes  173  extending toward the gate electrodes  124  and end portions (not shown) having a wide area for connection with a different layer or the IC chip  530 . The drain electrodes  175  are separated from the data lines  171  and are opposite to the source electrodes  173  with reference to the gate electrodes  124 . 
     A gate electrode  124 , a source electrode  173 , and a drain electrode  175  form a thin film transistor (TFT) together with a semiconductor  154 , and a channel of the TFT is formed in the semiconductor  154  between the source electrode  173  and the drain electrode  175 . 
     The ohmic contacts  163  and  165  are interposed only between the semiconductors  154  therebelow and the data lines  171  and drain electrodes  175  thereabove and the contact resistance between them is reduced. The semiconductors  154  have exposed portions that are not covered by the source electrodes  173  and the drain electrodes  175 . 
     A passivation layer  180  is formed on the exposed semiconductors  154 , the data lines  171 , the drain electrodes  175 , and the gate insulating layer  140 . 
     The passivation layer  180  has a plurality of contact holes  185  exposing the drain electrodes  175 . The passivation layer  180  and the gate insulating layer  140  have a plurality of contact holes (not shown) respectively exposing the end portions of the gate lines and the data lines  171 . 
     A plurality of pixel electrodes  191  are formed on the passivation layer  180 . The pixel electrodes  191  may be made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). 
     The pixel electrodes  191  are connected to the drain electrodes  175  through the contact holes  185 , and receive data voltages from the drain electrodes  175 . 
     A plurality of contact assistants may be formed on the passivation layer  180 . The contact assistants are respectively connected to the end portions of the gate lines and the data lines  171  through the contact holes. 
     An alignment layer  11  is formed on the pixel electrodes  191 . The alignment layer  11  may be made of an organic material or an inorganic material, for example, a polyimide may be used. 
     The thin film elements such as the above-described thin film transistors are formed on the transparent organic layer  115  such that operational defects due to the alkali components and the impurities included in the lower substrate  110  are not generated. Furthermore, the transparent organic layer  115  may be formed on the lower substrate  110 .  FIG. 6  is a graph showing an operation result of the thin film transistor according to existence and nonexistence a transparent organic layer  115  on the lower substrate  110 . The solid line in the graph shows the operation result when the transparent organic layer  115  exists on the lower substrate  110  made of a soda lime glass, and the dotted line shows the operation result when the transparent organic layer  115  does not exist on the lower substrate  110 . As shown in  FIG. 6 , under an off current (a reference to the gate voltage of −7V), the drain current is 1×10 −11  A in the case that the transparent organic layer  115  does not exist, and the drain current is 1×10 −12  A in the case that the transparent organic layer  115  exists. Under an on current (a reference to the gate voltage of 20V), the drain current has similar values whether the transparent organic layer  115  exists or not. Accordingly, the characteristics of the thin film transistor may benefit from the inclusion of the transparent organic layer  115 . 
     A transparent organic layer  215  is also formed on an upper substrate  210 . The upper substrate  210  is made of a soda lime glass like the lower substrate  110 . The transparent organic layer  215  is made of a polyimide, and contacts the upper substrate  210 . The transparent organic layer  215  may have the same transparency as the glass. The transparent organic layer  215  may have a transition temperature T g  of about 250° C. to about 450° C. Accordingly, the transparent organic layer  215  may be used in the high temperature process. The thermal expansion coefficient of the glass is in a range of about 3 ppm to about 80 ppm. The refractive index of the transparent organic layer  215  is in a range of about 1.5 to about 1.6, the sheet resistance thereof is in a range of about 1×10 17  Ωcm to about 2×10 17  Ωcm, the dielectric constant thereof is in a range of about 2.5 MHz to about 3.5 MHz, and the Young&#39;s modulus thereof is in a range of about 1.5 GPa to about 5 GPa. In general, an organic layer made of a polyimide may have a glass transition temperature of about 350° C. to about 550° C. 
     The transparent organic layer  215  may be formed on the upper substrate  210  through spin coating, slit coating, spin and slit coating, slot dying, or gravure printing, and may be hardened within a temperature range of about 150° C. to about 250° C. In this way, the transparent organic layer  215  may completely cover impurities that exist on the upper substrate  210 . Accordingly, the impurities and the alkali components that exist in the upper substrate  210  do not influence the thin film elements. 
     The thickness t of the transparent organic layer  215  may be in a range of about 0.3 μm to about 50 μm. When the thickness t of the transparent organic layer  215  is less than about 0.3 μm, it is difficult to uniformly form the transparent organic layer  215  on the upper substrate  210 , and the transparent organic layer  215  may not completely cover the impurities on the upper substrate  210  such that many defects may be generated during the manufacture of the display device. When the thickness t of the transparent organic layer  215  is more than about 50 μm, the transmittance is reduced and the transparent organic layer  215  may be bent during hardening. Furthermore, it is difficult to thickly form the transparent organic layer  215 , and when the thickness is increased, further advantageous effects are not generated. 
     A light blocking member  220  is formed on the transparent organic layer  215 . The light blocking member  220  includes a plurality of openings  225  facing the pixel electrodes  191  and having almost the same shape as the pixel electrodes  191 , thereby preventing light leakage between the pixel electrodes  191 . 
     An overcoat  250  is formed on the upper substrate  210  and the light blocking member  220 . The overcoat  250  may be made of an insulating material, and provides a flat surface. The overcoat  250  may be omitted. 
     A common electrode  270  is formed on the overcoat  250 , and the common electrode  270  is made of a transparent conductor such as ITO and IZO. A plurality of color filters  230  are formed between the transparent organic layer  215  and the overcoat  250 , and the overcoat  250  prevents the color filters  230  from being exposed. Each color filter  230  is at least partially in an opening  225  of the light blocking member  220 , and may display a primary color such as three primary colors of red, green, and blue. 
     A liquid crystal layer  3  is formed between the upper panel  200  and the lower panel  100 . 
     Next, an organic light emitting device according to an exemplary embodiment of the present invention will be described with reference to  FIG. 3  and  FIG. 4 . 
       FIG. 3  is a layout view of an organic light emitting device according to an exemplary embodiment of the present invention, and  FIG. 4  is a cross-sectional view of the organic light emitting device shown in  FIG. 3  taken along the line IV-IV. 
     A transparent organic layer  115  is formed on a substrate  110 . The substrate  110  is made of a soda lime glass. The transparent organic layer  115  is made of a polyimide and contacts the substrate  110 . The transparent organic layer  115  may have the same transparency as the glass. The transparent organic layer  115  may have a glass transition temperature T g  of about 250° C. to about 450° C. and it may be used in the high temperature process. The thermal expansion coefficient of the glass is in a range of about 3 ppm to about 80 ppm. Also, the refractive index of the transparent organic layer  115  is in a range of about 1.5 to about 1.6, the sheet resistance thereof is in a range of about 1×10 17  Ωcm to about 2×10 17  Ωcm, the dielectric constant thereof is in a range of about 2.5 MHz to about 3.5 MHz, and the Young&#39;s modulus thereof is in a range of about 1.5 GPa to about 5 GPa. 
     In general, an organic layer made of a polyimide may have a glass transition temperature of about 350° C. to about 550° C. 
     The transparent organic layer  115  may be formed on the substrate  110  through spin coating, slit coating, spin and slit coating, slot dying, or gravure printing, and may be hardened by a temperature in a range of about 150° C. to about 250° C. In this way, the transparent organic layer  115  may completely cover the impurities that exist on the substrate  110 . Accordingly, the impurities and the alkali components that exist in the substrate  110  do not influence the thin film elements. 
     The thickness t of the transparent organic layer  115  may be in a range of about 0.3 μm to about 50 μm. When the thickness t of the transparent organic layer  115  is less than about 0.3 μm, it may be difficult to uniformly form the transparent organic layer  115  on the substrate  110 , and the transparent organic layer  115  may not cover the impurities on the substrate  110  and defects may be generated during the manufacture of the display device. When the thickness t of the transparent organic layer  115  is more than about 50 μm, the transmittance is reduced and the transparent organic layer  115  may bend during hardening. Furthermore, it may be difficult to thickly form the transparent organic layer  115 , and when the thickness is increased, further advantageous effects are not generated. 
     A plurality of gate conductors including a plurality of gate lines  121  including first control electrodes  124   a  and a plurality of second control electrodes  124   b  are formed on the transparent organic layer  115 . 
     The gate lines  121  transmit gate signals and are substantially extended in the transverse direction. Each gate line  121  includes an end portion  129  having a large area for contact with another layer or an external driving circuit and the first control electrodes  124   a  that are extended from the gate lines  121 . The second control electrodes  124   b  are separated from the gate lines  121  including a storage electrode  127  extending in one direction. 
     A gate insulating layer  140  including a silicon nitride (SiNx) and/r silicon oxide (SiO2) is formed on the gate conductors  121 ,  124   a ,  124   b , and  127 . 
     A plurality of first semiconductors  154   a  and a plurality of second semiconductors  154   b , for example, including hydrogenated amorphous silicon and/or polysilicon are formed on the gate insulating layer  140 . The first semiconductors  154   a  overlap the first control electrodes  124   a  and the second semiconductors  154   b  overlap the second control electrodes  124   b.    
     A plurality of first ohmic contacts  163   a  and  165   a  and a plurality of second ohmic contacts  163   b  and  165   b  are respectively formed on the first and second semiconductors  154   a  and  154   b . The first ohmic contacts  163   a  and  165   a  are disposed as a pair on the first semiconductors  154   a , and the second ohmic contacts  163   b  and  165   b  are disposed as a pair on the second semiconductors  154   b.    
     A plurality of data conductors including a plurality of data lines  171 , a plurality of driving voltage lines  172 , and a plurality of first and second output electrodes  175   a  and  175   b  are formed on the ohmic contacts  163   a ,  163   b ,  165   a , and  165   b  and the gate insulating layer  140 . 
     The data lines  171  transmitting data signals extend substantially in the longitudinal direction and intersect the gate lines  121 . Each data line  171  includes a plurality of first input electrodes  173   a  extended toward the first control electrodes  124   a  and an end portion  179  having a large area for contact with another layer or an external driving circuit. 
     The driving voltage lines  172  for transmitting driving voltages extend substantially in the longitudinal directional, and intersect the gate lines  121 . Each of the driving voltage lines  172  includes a plurality of second input electrodes  173   b  extending toward the second control electrodes  124   b , and portions overlapping the storage electrodes  127 . 
     The first and second output electrodes  175   a  and  175   b  are separated from each other, as well as from the data lines  171  and the driving voltage lines  172 . The first input electrode  173   a  and the first output electrode  175   a  are opposite to each other with respect to the first control electrode  124   a . The second input electrode  173   b  and the second output electrode  175   b  are opposite to each other with respect to the second control electrode  124   b.    
     A passivation layer  180  is formed on the data conductors  171 ,  172 ,  175   a , and  175   b  and the exposed semiconductors  154   a  and  154   b . The passivation layer  180  may be made of an inorganic insulator or an organic insulator and may have a flat surface. 
     The passivation layer  180  has a plurality of contact holes  182 ,  185   a ,  185   b  respectively exposing the end portions of the data lines  171  and the first and the second output electrodes  175   a  and  175   b . The passivation layer  180  and the gate insulating layer  140  have a plurality of contact holes  181  and  184  respectively exposing the end portions  129  of the gate lines  121  and the second control electrodes  124   b.    
     A plurality of pixel electrodes  191 , a plurality of connecting members  85 , and a plurality of contact assistants  81  and  82  are formed on the passivation layer  180 . The connecting members  85  are respectively connected to the second control electrodes  124   b  and the first output electrodes  175   a  through the contact holes  184  and  185   a . The contact assistants  81  and  82  are connected to the end portions  129  of the gate lines  121  and the end portions  179  of the data lines  171  through the contact holes  181  and  182 , respectively. 
     A partition  361  is formed on the passivation layer  180 . The partition  361  surrounds the edges of the pixel electrodes  191  and is made of an organic insulator and/or an inorganic insulator. The partition  361  may be made of a photosensitive material including black pigments, and the partition  361  functions as a light blocking member in this case. 
     A plurality of organic light emitting members  370  are formed on the pixel electrodes  191  and a common electrode  270  is formed on the organic light emitting members  370 . An encapsulation layer (not shown) may be formed on the common electrode  270 . The encapsulation layer encapsulates the organic light emitting members  370  and common electrode  270  and blocks moisture and/or oxides from penetrating from the outside. 
     The thin film elements such as the above-described thin film transistors are formed on the transparent organic layer  115  and operational defects due to the alkali components and the impurities included in the lower substrate  110  may be avoided. 
     Next, an electrophoretic display according to an exemplary embodiment of the present invention will be described in detail with reference to  FIG. 5 . 
       FIG. 5  is a cross-sectional view of an electrophoretic display according to an current exemplary embodiment of the present invention. 
     Referring to  FIG. 5 , an electrophoretic display includes a lower panel  100 , an upper panel  200 , a plurality of partitions  361 , and electrophoretic particles  315 . 
     In the lower panel  100 , a transparent organic layer  115  is formed on the lower substrate  110 . The lower substrate  110  is made of a soda lime glass. The transparent organic layer  115  is made of a polyimide, and contacts the lower substrate  110 . The transparent organic layer  115  may have the same transparency as the glass. The transparent organic layer  115  may have a glass transition temperature of about 250° C. to about 450° C. such that it may be used in a high temperature process, and the thermal expansion coefficient thereof is in a range of about 3 ppm to about 80 ppm. Also, the refractive index of the transparent organic layer  115  is in a range of about 1.5 to about 1.6, the sheet resistance thereof is in a range of about 1×10 17  Ωcm to about 2×10 17  Ωcm, the dielectric constant thereof is in a range of about 2.5 MHz to about 3.5 MHz, and the Young&#39;s modulus thereof is in a range of about 1.5 GPa to about 5 GPa. 
     In general, an organic layer made of a polyimide may have a glass transition temperature of about 350° C. to about 550° C. 
     The transparent organic layer  115  may be formed on the lower substrate  110  through spin coating, slit coating, spin and slit coating, slot dying, or gravure printing, and may be hardened in a temperature range of about 150° C. to about 250° C. In this way, the transparent organic layer  115  may completely cover the impurities that exist on the lower substrate  110 . Accordingly, the impurities and the alkali components that exist in the lower substrate  110  do not influence the other thin film elements. 
     The thickness t of the transparent organic layer  115  may be in a range of about 0.3 μm to about 50 μm. When the thickness t of the transparent organic layer  115  is less than about 0.3 μm, it may be difficult to uniformly form the transparent organic layer  115  on the lower substrate  110 , and the transparent organic layer  115  may not cover the impurities on the lower substrate  110 . Accordingly, defects may be generated during the manufacture of the display device. When the thickness t of the transparent organic layer  115  is more than about 50 μm, the transmittance is reduced and the transparent organic layer  115  may bend during hardening. Furthermore, it is difficult to thickly form the transparent organic layer  115 , and when the thickness increases, further advantageous effects are not generated. 
     A gate conductor including a plurality of gate lines (not shown) and a plurality of storage electrode lines (not shown) is formed on the transparent organic layer  115 . The gate lines transmit gate signals and include a plurality of gate electrodes  124 . The storage electrode lines include a plurality of common electrodes  270  and a plurality of storage electrodes  133 . The common electrodes  270  may be formed on the upper substrate  210 . 
     A gate insulating layer  140 , a plurality of semiconductor islands  154 , a plurality of pairs of ohmic contact islands  163  and  165 , a plurality of data lines  171 , and a plurality of drain electrodes  175  are sequentially formed on the gate conductor. 
     The data lines  171  transmit data signals, and include a plurality of source electrodes  173 . The drain electrodes  175  are separated from the data lines  171  and are opposite to the source electrodes  173  with respect to the gate electrodes  124 . 
     A gate electrode  124 , a source electrode  173 , and a drain electrode  175  form a thin film transistor (TFT) together with the semiconductor  154 . A channel of the TFT is formed in the semiconductor  154  between the source electrode  173  and the drain electrode  175 . 
     A passivation layer  180  is formed on the exposed semiconductors  154 , the data lines  171 , the drain electrodes  175 , and the gate insulating layer  140 . The passivation layer  180  has a plurality of contact holes  185  exposing the drain electrodes  175 . 
     A plurality of pixel electrodes  191  are formed on the passivation layer  180 . The pixel electrodes  191  overlap the storage electrodes  133  and do not overlap the common electrode  270 . The pixel electrodes  191  are connected to the drain electrodes  175  through the contact holes  185 , and receive data voltages from the drain electrodes  175 . 
     The thin film elements such as the above-described thin film transistors are formed on the transparent organic layer  115  and operational defects due to the alkali components and the impurities included in the lower substrate  110  may be avoided. 
     In the upper panel  200 , a light blocking member  220  is formed on the upper substrate  210 . The light blocking member  220  overlaps the common electrode  270  and blocks incident light from the outside. 
     The upper substrate  210  may be made of an alkali-containing glass, and a transparent organic layer made of polyimide may be formed on the upper substrate  210  in this case. 
     The electrophoretic particles  315  are interposed in the gap between the lower panel  100  and the upper panel  200 , and are divided by the partitions  361 . The partitions  361  may be fixed on the passivation layer  180  and close to the upper panel  200 . 
     The electrophoretic particles  315  may represent one of red, green, blue, yellow, magenta, cyan, and white, and have a reflective quality. 
     While exemplary embodiments of the present invention have been described with reference to the figures, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements.