Organic light emitting diode back plate and method of manufacturing same

A method of manufacturing an OLED back plate and an OLED back plate are provided. The method includes: providing a TFT substrate and forming an electrode layer on the TFT substrate; forming a pixel defining layer on the electrode layer by using a first mask, and forming a plurality of pixel units, each of the pixel units includes a light emitting area, and an inter-pixel area is formed between adjacent two of the pixel units; etching the electrode layer corresponding to the inter-pixel area; removing the pixel defining layer corresponding to the light emitting area to form a pixel opening; and forming a barrier block on adjacent two of the pixel defining layers of adjacent two of the pixel units by a second mask, and the barrier block does not completely cover the pixel defining layer.

FIELD OF INVENTION

This disclosure relates to the field of display technology, and more particularly, to a method of manufacturing an organic light emitting diode (OLED) back plate and the OLED back plate.

BACKGROUND OF INVENTION

Organic light emitting diode (OLED) displays have the advantages of self-illumination, low driving voltage, high luminous efficiency, short response times, high resolution and contrast ratios, wide viewing angles, wide temperature ranges, flexible display, large area full color display, and others. The OLED displays are recognized by the industry as the most promising display devices.

In consideration of the enlargement of the OLED display and the cost reduction of OLED materials, inkjet printing (IJP) technology, which is suitable for the development of large-sized OLED displays, has been developed in addition to the conventional vapor deposition in the OLED manufacturing processes. In order to ensure the quality of an OLED display panel manufactured by the inkjet printing, the ink is dropped into a predetermined light emitting region and is needed to be spread evenly. Moreover, inks in different colors should not be mixed.

A pixel defining layer in a conventional OLED back plate is formed by forming a patterned anode layer on a TFT substrate1, and forming barriers2around each of pixel units3using a hydrophobic material, as shown inFIG. 1. However, the conventional barriers2do not make ink droplets spread evenly over the predetermined light emitting regions, as shown inFIG. 2A. When the printed inks are solidified, excessive contact angles of the ink droplets I close to lateral sides of the barriers2occur, so that a thickness T1of a portion of the ink droplets I close to lateral sides of the barriers is much larger than a thickness T2of a portion of the ink droplets I away from the lateral sides of the barriers2(i.e., corresponding to the middle of the light emitting region), as shown inFIG. 2B. Thus, the uniformity of the ink droplets I in the pixel units3is poor, affecting the subsequent processes and the display effects. In addition, the ink droplets between adjacent two pixel units may also cause the problem of color mixture.

SUMMARY OF INVENTION

An object of the disclosure is to provide a method of manufacturing an organic light emitting diode (OLED) back plate and the OLED back plate to solve the technical problems that the conventional barriers2do not make ink droplets spread evenly over the predetermined light emitting regions. When the printed inks are solidified, excessive contact angles of the ink droplets I close to lateral sides of the barriers2occur, so that a thickness of a portion of the ink droplets close to lateral sides of the barriers is much larger than a thickness of a portion of the ink droplets away from the lateral sides of the barriers2(i.e., corresponding to the middle of the light emitting region). Thus, the uniformity of the ink droplets in the pixel units3is poor, affecting the subsequent processes and the display effects. In addition, the ink droplets between adjacent two pixel units may also cause the problem of color mixture.

In order to solve the above problems, the disclosure provides a method of manufacturing an OLED back plate. The method comprises steps of:

providing a TFT substrate, and forming an electrode layer on the TFT substrate;

forming a pixel defining layer on the electrode layer by using a first mask, and forming a plurality of pixel units, wherein each of the pixel units comprises a light emitting area, and an inter-pixel area is formed between adjacent two of the pixel units;

etching the electrode layer corresponding to the inter-pixel area;

removing the pixel defining layer corresponding to the light emitting area to form a pixel opening; and

forming a barrier block on adjacent two of the pixel defining layers of adjacent two of the pixel units by a second mask.

In an embodiment of the disclosure, a recess is formed on a top surface of the barrier block.

In an embodiment of the disclosure, the barrier block is made of a hydrophobic material.

In an embodiment of the disclosure, the first mask is a halftone mask or a grayscale mask.

In an embodiment of the disclosure, the pixel defining layer is made of a photosensitive material.

In an embodiment of the disclosure, the barrier block extends from the pixel defining layer to adjacent two of the electrode layers between the adjacent two of the pixel units.

In an embodiment of the disclosure, the first mask comprises a light transmission area and a half light transmission area, the light transmission region corresponds to the inter-pixel area, and the half light transmission region corresponds to the light emitting area.

In an embodiment of the disclosure, a projection area of the inter-pixel area is smaller than a projection area of an area between the electrode layers of adjacent two of the pixel units.

In an embodiment of the disclosure, the pixel defining layer is disposed around the pixel opening, and the barrier block is disposed around the pixel opening.

The disclosure further provides an OLED back plate. The OLED back plate comprises:

a TFT substrate; and

a plurality of pixel units disposed on the TFT substrate. An inter-pixel area is disposed between adjacent two of the pixel units.

Each of the pixel units comprises an electrode layer, a pixel defining layer disposed on the electrode layer and a barrier block. A pixel opening is disposed on the pixel defining layer above the electrode layer, and the barrier block is disposed on adjacent two of the pixel defining layers of adjacent two of the pixel units.

In an embodiment of the disclosure, a recess is disposed on a top surface of the barrier block.

In an embodiment of the disclosure, the barrier block is made of a hydrophobic material.

In an embodiment of the disclosure, the pixel defining layer is made of a photosensitive material.

In an embodiment of the disclosure, the barrier block extends from the pixel defining layer to adjacent two of the electrode layers between the adjacent two of the pixel units.

In an embodiment of the disclosure, a projection area of the inter-pixel area is smaller than a projection area of an area between the electrode layers of adjacent two of the pixel units.

In an embodiment of the disclosure, the pixel defining layer is disposed around the pixel opening, and the barrier block is disposed around the pixel opening.

The technical effects are as follows. The disclosure provides a method of manufacturing an OLED back plate and the OLED back plate. The pixel defining layer is formed on the anode layer by the first mask, the barrier block is formed on the pixel defining layer by the second mask, and the barrier block does not completely cover the pixel defining layer. Under the premise that the number and use times of the mask are not increased, a portion of the pixel unit corresponding to an ink droplet having a large thickness close to a side of the barrier block is covered by the pixel defining layer, so that light cannot be emitted from the portion, and a portion of the pixel unit corresponding to an ink droplet having a small thickness away from a side of the barrier block is not covered by the pixel defining layer, so that light is emitted from the portion. The thickness of the ink droplets away from the lateral side of the barrier block (i.e., the pixel opening, the light emitting area of the pixel unit) is uniform, and the uniformity of the ink droplets in the light emitting area of the pixel unit is improved. In addition, the recess of the barrier block can accommodate excess ink droplets. The excess ink droplets flow into the recess without flowing into the adjacent pixel units. Therefore, the amount of ink droplets in each pixel unit can be controlled, and the ink droplets between the two pixel units can be prevented from being mixed, so that the subsequent products can achieve an ideal display effect.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In order to more clearly describe the embodiments of the disclosure, the description is used to make a simple introduction of the drawings used in the following embodiments.

Referring toFIG. 3AtoFIG. 3E,FIG. 4, andFIG. 5, the disclosure provides a method of manufacturing an OLED back plate. The method comprises the following steps.

In a step S01, a TFT substrate10is provided, and an electrode layer20is formed on the TFT substrate10, as shown inFIG. 3A.

In a step S02, a pixel defining layer30is formed on the electrode layer20by using a first mask (not shown), thereby forming a plurality of pixel units50. Each of the pixel units50comprises a light emitting area A, and an inter-pixel area D is formed between adjacent two of the pixel units50, as shown inFIG. 3B.

In a step S03, the electrode layer20corresponding to the inter-pixel area D is etched, as shown inFIG. 3C.

In a step S04, the pixel defining layer30corresponding to the light emitting area A is removed to form a pixel opening31, as shown inFIG. 3D.

In a step S05, a barrier block60is formed on adjacent two of the pixel defining layers30of adjacent two of the pixel units50by a second mask (not shown), as shown inFIG. 3E.

Specifically, a TFT array layer12and an electrode layer film are formed on a substrate11to form the TFT substrate10. In some embodiments, a planar layer13may be formed between the TFT array layer12and the anode layer20. The pixel defining layer30is fabricated by using a first mask, which is a halftone mask or a grayscale mask. The first mask comprises a light transmission area and a half light transmission area, the light transmission region corresponds to the inter-pixel area D, and the half light transmission region corresponds to the light emitting area A.

The substrate10may be a flexible substrate, such as a polyimide film. The substrate10may also be a rigid substrate, such as a quartz substrate or a glass substrate.

Specifically, a material of the electrode layer20is a multi-layer structure composed of indium tin oxide or indium tin oxide-silver-indium tin oxide (ITO/Ag/ITO).

The electrode layer20is then etched, and the pixel defining layer30corresponding to the light emitting area A is removed by a plasma etching process. The pixel defining layer30is disposed around the periphery of the pixel unit50. For the pixel defining layer30, the light emitting area A is exposed to form the pixel opening31, such that the pixel defining layer30is disposed around the pixel opening31, and the barrier block60is disposed around the pixel opening31.

Then, the barrier block60is formed across the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50by using the second mask. In more detail, the barrier block60is disposed on both of the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50, and may be a trapezoidal structure, but is not limited thereto. A width W1of the barrier block60is less than a sum of the two respective widths W2of the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50and a width W3of the inter-pixel area D. That is, the barrier block60only partially covers the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50, respectively. Moreover, the barrier block60extends from the pixel defining layer30to a place between the adjacent two of the electrode layers20between the adjacent two of the pixel units50to prevent the overflowed ink from flowing to the place between the adjacent two of the electrode layers20. Besides, the barrier block60is made of a hydrophobic material, and the pixel defining layer30is made of a photosensitive material.

In addition, a top surface of the barrier block60comprises a recess61. According to an embodiment of the present disclosure, a projection area of the inter-pixel area D is smaller than a projection area of an area between the electrode layers20of adjacent two of the pixel units50. That is, the electrode layer is over-etched to facilitate the fabrication of the recess61. The recess61can accommodate excess ink droplets, and the excess ink droplets can flow into the recess61, rather than flowing into the adjacent pixel unit(s)50.

Finally, the subsequent evaporation and packaging process is performed to complete the manufacturing of the OLED back plate.

Referring toFIG. 5, the disclosure further provides an OLED back plate. The OLED back plate comprises a TFT substrate10, a plurality of pixel units50, and a barrier block60.

The plurality of pixel units50is disposed on the TFT substrate10. A predetermined interval is disposed between adjacent two of the pixel units50. That is to say, an inter-pixel area D is disposed between adjacent two of the pixel units50.

Each of the pixel units50comprises an electrode layer20, and a pixel defining layer30disposed on the electrode layer20. A pixel opening31is defined by the pixel defining layer30above the electrode layer20. The barrier block60is disposed on adjacent two of the pixel defining layers30of adjacent two of the pixel units50.

The TFT substrate10includes a substrate11, a TFT array layer12, and a planar layer13. The planar layer13is disposed between the electrode layer20(the anode layer) and the TFT array layer12.

The substrate10may be a flexible substrate such as a polyimide film. The substrate10may also be a rigid substrate such as a quartz substrate or a glass substrate.

Specifically, a material of the electrode layer20is a multi-layer structure composed of indium tin oxide or indium tin oxide-silver-indium tin oxide (ITO/Ag/ITO).

The pixel defining layer30is disposed around the periphery of the pixel unit50. The pixel defining layer30exposes the light emitting area A to form the pixel opening31, such that the pixel defining layer30is disposed around the pixel opening31, and the barrier block60is disposed around the pixel opening31.

In more detail, the barrier block60is formed across the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50by using the second mask. In more detail, the barrier block60is disposed on both of the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50, and may be a trapezoidal structure, but is not limited thereto. A width W1of the barrier block60is less than a sum of the two respective widths W2of the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50and a width W3of the inter-pixel area D. That is, the barrier block60only partially covers the adjacent two of the pixel defining layers30of the adjacent two of the pixel units50, respectively. Moreover, the barrier block60extends from the pixel defining layer30to a place between the adjacent two of the electrode layers20between the adjacent two of the pixel units50to prevent the overflowed ink from flowing to the place between the adjacent two of the electrode layers20. Besides, the barrier block60is made of a hydrophobic material, and the pixel defining layer30is made of a photosensitive material.

In addition, a top surface of the barrier block60comprises a recess61. According to an embodiment of the present disclosure, a projection area of the inter-pixel area D is smaller than a projection area of an area between the electrode layers20of adjacent two of the pixel units50. That is, the electrode layer is over-etched to facilitate the fabrication of the recess61. The recess61can accommodate excess ink droplets, and the excess ink droplets can flow into the recess61, rather than flowing into the adjacent pixel unit50, as shown inFIG. 6A. The recess accommodates excess droplets for achieving the effect of preventing different colors of ink droplets belonging to different pixel units from mixing with each other.

The pixel defining layer30is disposed between the electrode layer20and the barrier block60. As shown inFIG. 6B, a thickness D1of the ink droplets I close to a lateral side of the barrier block60is relatively larger than a thickness D2of the ink droplets I away from the lateral side (i.e., in the middle of the light emitting area) of the barrier block60. A region where the thickness of the ink droplet is relatively larger is covered by the pixel defining layer30, so that light is not emitted from the region, and light only emitted from a region (the light emitting area A) comprising a consistent thickness of the ink droplets, and an uniform light emitting effect can be obtained.

The technical effects are as follows. The disclosure provides a method of manufacturing an OLED back plate and the OLED back plate. The pixel defining layer is formed on the anode layer by the first mask, the barrier block is formed on the pixel defining layer by the second mask, and the barrier block does not completely cover the pixel defining layer. Under the premise that the number and use times of the mask are not increased, a portion of the pixel unit corresponding to an ink droplet having a large thickness close to a side of the barrier block is covered by the pixel defining layer, so that light cannot be emitted from the portion, and a portion of the pixel unit corresponding to an ink droplet having a small thickness away from a side of the barrier block is not covered by the pixel defining layer, so that light is emitted from the portion. The thickness of the ink droplets away from the lateral side of the barrier block (i.e., the pixel opening, the light emitting area of the pixel unit) is uniform, and the uniformity of the ink droplets in the light emitting area of the pixel unit is improved. In addition, the recess of the barrier block can accommodate excess ink droplets. The excess ink droplets flow into the recess without flowing into the adjacent pixel units. Therefore, the amount of ink droplets in each pixel unit can be controlled, and the ink droplets between the two pixel units can be prevented from being mixed, so that the subsequent products can achieve an ideal display effect.

This disclosure has been described with preferred embodiments thereof, and it is understood that many changes and modifications to the described embodiment can be carried out without departing from the scope and the spirit of the invention.