Organic light emitting diode (OLED) display panel with reflective electrode

An organic light emitting diode (OLED) display panel includes a substrate, a reflective electrode disposed on the substrate, and a pixel define layer (PDL) formed on the substrate and the reflective electrode layer. The reflective electrode layer has multiple reflective structures, and each reflective structure has a first region and a second region. The PDL is provided with multiple openings corresponding to the reflective structures, such that the first region and the second region of each of the reflective structures are exposed in a corresponding one of the openings. Multiple organic emissive structures are correspondingly formed in the openings and covering the reflective structures, forming a plurality of pixels. For each respective pixel of the pixels, a first reflective ratio of the respective pixel corresponding to the first region is greater than a second reflective ratio of the respective pixel corresponding to the second region.

FIELD

The disclosure relates generally to display technology, and more particularly to an organic light emitting diode (OLED) display panel that solves.

BACKGROUND

Currently, organic light emitting diode (OLED) display panels are widely used in mobile devices such as cell phones or tablet devices. In some cases, the OLED display panel may be an active matrix OLED (AMOLED) display panel, which is used in a device that require a higher resolution, such as in a virtual reality (VR) device. With the resolution of the OLED display panel being increased, the size of each emissive structure in an emissive layer of the OLED display panel may be small, and accurate coating alignment for the emissive structures may become more difficult.

SUMMARY

One aspect of the disclosure relates to an organic light emitting diode (OLED) display panel, which includes: a substrate; a reflective electrode layer disposed on the substrate and having a plurality of reflective structures, wherein each of the reflective structures has a first region and a second region; a pixel define layer (PDL) formed on the substrate and the reflective electrode layer, wherein the PDL is provided with a plurality of openings corresponding to the reflective structures, such that the first region and the second region of each of the reflective structures are exposed in a corresponding one of the openings; and a plurality of organic emissive structures correspondingly formed in the openings and covering the reflective structures, forming a plurality of pixels, wherein for each respective pixel of the pixels, a first reflective ratio of the respective pixel corresponding to the first region is greater than a second reflective ratio of the respective pixel corresponding to the second region.

In certain embodiments, the OLED display panel has a total reflective ratio greater than or equal to 80%.

In certain embodiments, a first area ratio of the first region is X of a total area of each of the reflective structures, a second area ratio of the second region is (1-X) of the total area of each of the reflective structures, and X is greater than or equal to 80% and less than or equal to 99%.

In certain embodiments, for each of the reflective structures, a difference between the first reflective ratio of the first region and the second reflective ratio of the second region is greater than or equal to 1%.

In certain embodiments, for each of the reflective structures, the first region and the second region are formed with a same material and have different thicknesses, such that the first reflective ratio of the first region is greater than the second reflective ratio of the second region.

In certain embodiments, the material is selected from a group consisting of Ag, Al, Mg and Mo, and a first thickness of the first region is greater than a second thickness of the second region.

In certain embodiments, for each of the reflective structures, the first region and the second region are formed with different materials and have a same thickness, such that the first reflective ratio of the first region is greater than the second reflective ratio of the second region.

In certain embodiments, each of the different materials is selected from a group consisting of Ag, Al, Mg and Mo.

In certain embodiments, the first region is surrounded by the second region.

In certain embodiments, the second region is divided into two separate areas by the first region.

In certain embodiments, a thickness of each of the reflective structures is less than or equal to 100 nm.

In certain embodiments, for each of the reflective structures, a thickness of the first region is less than or equal to 100 nm and greater than or equal to 40 nm.

In certain embodiments, each of the reflective structures further has a third region between the first region and the second region, and for each respective pixel of the pixels, a third reflective ratio of the respective pixel corresponding to the third region is greater than the second reflective ratio and less than the first reflective ratio.

In certain embodiments, the OLED display panel has a resolution greater than 600 pixels per inch (ppi).

In certain embodiments, the reflective structures in function as anodes of the pixels, and each of the reflective structures is respectively covered and sandwiched by two transparent layers. In one embodiment, the transparent layers are indium tin oxide (ITO) layers.

In certain aspects of the disclosure, a device may have the OLED display panel as discussed above. In certain embodiment, the device may be a virtual reality (VR) device.

DETAILED DESCRIPTION OF THE DISCLOSURE

Unless otherwise specified, the term “reflective ratio” as used herein refers to a relative reflective ratio using the actual reflective ratio of a layer of silver (Ag) having a thickness of 100 nm or more as the basis. Specifically, the actual reflective ratio of the Ag layer having a thickness over 100 nm reaches a stably high ratio substantially close to 100%. Thus, using the actual reflective ratio of the Ag layer over 100 nm as the basis, the “reflective ratio” as used herein would be approximately similar to the actual reflective ratio.

The description will be made as to the embodiments of the present disclosure in conjunction with the accompanying drawings. In accordance with the purposes of this disclosure, as embodied and broadly described herein, this disclosure, in certain aspects, relates to an OLED display panel having a specific design for its reflective structures of a reflective electrode layer, such that each pixel of the OLED display panel may have two different reflective ratios in two regions of the corresponding reflective structure.

As discussed above, an OLED display panel, such as an AMOLED display panel, may be used in a device that require a higher resolution Currently, the resolution of a typical AMOLED display panel may be in a range of 400-600 pixels per inch (ppi). However, in some cases where the image being displayed on the AMOLED display panel is enlarged, the resolution may be considered low. For example,FIG. 1Aschematically shows an image100displayed by an OLED display panel according to certain embodiments of the present disclosure, andFIG. 1Bschematically shows a partially enlarged view of the image inFIG. 1A. Specifically, the image100as shown inFIG. 1Ais a VR image, where a distance of the VR image100is about 20-30 cm from the user eyes, andFIG. 1Bshows an enlarged view of the VR image100, where the distance of the enlarged view120is about 6 cm from the user eyes. As shown inFIG. 1B, the enlarged view120of the image100shows a grainy mesh pattern, which is apparently observable to human eyes. Since a user may frequently use the magnifying function to enlarge the VR images in the VR application, the resolution of the OLED display panel must be increased to avoid the significant grainy mesh pattern issue.

However, to manufacture an OLED display panel with a higher resolution, the pixel size of the OLED display panel must be reduced. For example,FIG. 2schematically shows a vacuum deposition process of the emissive layers of an OLED display panel according to certain embodiments of the present disclosure. Specifically, the vacuum deposition process is a part of the manufacturing process of the OLED display panel. In the process as shown inFIG. 2, an emissive layer220(i.e., a pixel layer) is deposited on a substrate210by vacuum deposition using a fine mask shadow mask (FMM)230and a vacuum source240. As shown inFIG. 2, the emissive layer220includes multiple emissive structures in RGB colors, and the mask openings235of the FMM230are aligned to the emissive structures in the red (R) color. Thus, all of the emissive structures in the red (R) color are formed altogether in one step of the vacuum deposition process, and the emissive structures in the green (G) color and the emissive structures in the blue (B) color require two more respective steps of the vacuum deposition process.

In the vacuum deposition process using the FMM230as shown inFIG. 2, two major factors are involved as the restrictions to the vacuum deposition process: (1) the size of each mask opening235of the FMM230, and (2) the alignment of the mask openings235of the FMM230to the intended positions of the corresponding emissive structures in the emissive layer220on the substrate210. With a higher resolution of the OLED display panel being required, the size of each emissive structure in the emissive layer220may be small. Since the size of each emissive structure in the emissive layer220is determined by the size of each mask opening235of the FMM230, the size of each mask opening235of the FMM230is also correspondingly reduced. Thus, a slight deviation of the FMM230from its intended location in the vacuum deposition process may cause the emissive structures in one color to shift from their corresponding positions on the substrate210. Thus, accurate coating alignment for the emissive structures in the emissive layer220may become more difficult.

When some of the emissive structures in the emissive layer220shift from their intended positions on the substrate210, a portion of the shifted emissive structures may overlap with their adjacent emissive structures. For example,FIG. 3Aschematically shows an OLED display panel according to certain embodiments of the present disclosure, in which the G emissive structure overlaps with the adjacent R emissive structure. As shown inFIG. 3A, the OLED display panel300includes a hole injection layer (HIL)310, a hole transport layer (HTL)320, and an emissive layer330(i.e., the pixel layer) including multiple emissive structures330R,330G and330B. Specifically, the HIL310and the HTL320are optional structures, and in certain embodiments, the OLED display panel300may include only one of the HIL310and the HTL320. As shown inFIG. 3A, the HIL310includes a plurality of HIL structures310R,310G and310B corresponding to the emissive structures330R,330G and330B. Further, the emissive structures in the emissive layer330are shown in different rows to illustrate the shift of the green (G) emissive structure330G. In the emissive layer330, the blue (B) emissive structures330B and the red (R) emissive structure330R are respectively located in their respective positions. However, the green (G) emissive structure330G shifts rightward from its intended position330G′ (shown in dotted line), thus forming an overlapping area335with the adjacent red (R) emissive structure330R. Thus, the light emitted in the overlapping area335is a mix of light in the R/G colors, which becomes a yellow (Y) light340.FIG. 3Bshows emission of an OLED display panel with mixing of R/G colors according to certain embodiments of the present disclosure, in which the emission of the overlapping area360shows a yellow pattern due to the upward shift of the green (G) emissive structure.

FIG. 4Aschematically shows a sectional view of an OLED display panel according to certain embodiments of the present disclosure. As shown inFIG. 4A, the OLED display panel400includes a substrate410, a reflective electrode layer having multiple reflective structures420R,420G and420B, a pixel define layer (PDL)430, a plurality of organic emissive structures440R,440G and440B, and a transparent electrode450. The reflective electrode layer is disposed on the substrate410.

As shown inFIG. 4A, the reflective structures420R,420G and420B are disposed on the substrate410.FIG. 4Bschematically shows a sectional view of a reflective structure of the OLED display panel inFIG. 4A. As shown inFIG. 4B, the reflective structure420is respectively covered and sandwiched by two transparent layers424and426, thus forming a sandwiched structure. The transparent layers424and426may be indium tin oxide (ITO) layers, and each of the transparent layers424and426is relatively thin in comparison to the reflective structure420such that the reflective ratio of the reflective structure420is not significantly affected by the transparent layers424and426.

Referring back toFIG. 4A, the PDL430is formed on the substrate410and the reflective electrode layer. The PDL430is provided with a plurality of opening corresponding to the reflective structures420R,420G and420B, and the organic emissive structures440R,440G and440B are correspondingly formed in the openings and covering the reflective structures420R,420G and420B. In certain embodiments, each reflective structure may be directly in contact with the corresponding organic emissive structure. Alternatively, in certain embodiments, there may be other films or layers (such as the HIL, HTL or other layers) between each reflective structure and the corresponding organic emissive structure such that each reflective structure is not directly in contact with the corresponding organic emissive structure. The transparent electrode450is disposed on the PDL430and the organic emissive structures440R,440G and440B. The structures collectively form a plurality of OLED pixels, in which each of the reflective structures functions as an anode of the corresponding pixel, and the transparent electrode450functions as the cathode for each of the pixels.

As discussed above, when some of the organic emissive structures440R,440G and440B shift from their intended positions, a portion of the shifted organic emissive structures may overlap with their adjacent organic emissive structures. For example,FIG. 4Cschematically shows a sectional view of the OLED display panel inFIG. 4A. As shown inFIG. 4C, the organic emissive structure440G of the green (G) pixel shifts leftward and partially overlaps with the organic emissive structure440R of the red (R) pixel, forming an overlapping area460. Further, the transparent electrode450inFIG. 4Cis removed to better illustrate the overlapping area460. The mix of light in the R/G colors in the overlapping area460between the organic emissive structures440R and440G may results in the unwanted yellow pattern as shown inFIG. 3B.

In order to solve the unwanted mixing color patterns caused by the shift of the organic emissive structures, one aspect of the disclosure relates to an OLED display panel, in which each reflective structure has multiple regions with different reflective ratios. Specifically, the reflective ratio of a first region of each reflective structure which does not correspond to the overlapping area is greater than the reflective ratio of a second region of each reflective structure corresponding to the overlapping area, such that the reflective ratio of each pixel corresponding to the second region may be reduced, thus reducing the unwanted mixing color patterns. In certain embodiments, for each of the reflective structures, a difference between the reflective ratio of the first region and the reflective ratio of the second region is greater than or equal to 1%, such that the human eyes may detect the difference between the luminance corresponding to the first region and the second region.

FIG. 5Aschematically shows a sectional view of an OLED display panel according to certain embodiments of the present disclosure, in which each reflective structure has two regions. As shown inFIG. 5A, the OLED display panel500includes a substrate510, a reflective electrode layer having multiple reflective structures520R,520G and520B, a PDL530, a plurality of organic emissive structures540R,540G and540B, and a transparent electrode550. Specifically, the difference between the OLED display panel500as shown inFIG. 5Afrom the OLED display panel400as shown inFIG. 4Aexists in that each of the reflective structures520R,520G and520B has two regions. Specifically, the reflective structure520R has a first region522R and a second region524R, the reflective structure520G has a first region522G and a second region524G, and the reflective structure520B has a first region522B and a second region524B. Other structures of the OLED display panel500, including the substrate510, the PDL530, the organic emissive structures540R,540G and540B, and the transparent electrode550, are similar to the corresponding structures of the OLED display panel400as shown inFIG. 4A, and are thus not elaborated herein.

FIG. 5Bschematically shows a top view of a reflective structure having two regions inFIG. 5A. As shown inFIG. 5B, the reflective structure520is substantively a square-shaped structure, which is divided into a first region (M1)522and a second region (M2)524surrounding the first region M1, and a first area ratio of the first region M1is 80% of a total area of the reflective structure520. In other words, a second area ratio of the second region M2is 20% of the total area of the reflective structure520. Further, a first reflective ratio of the first region M1is greater than a second reflective ratio of the second region M2. For example, if the first reflective ratio of the first region M1is designated as being 100%, the second reflective ratio of the second region M2must be less than 100%.

As shown inFIG. 5A, the PDL530is provided with a plurality of opening corresponding to the reflective structures520R,520G and520B, such that the first region M1and the second region M2of each reflective structure are exposed in the corresponding opening. In certain embodiments, the first region M1and the second region M2of each reflective structure are directly in contact with the corresponding organic emissive structure. Alternatively, in certain embodiments, there may be other films or layers (such as the HIL, HTL or other layers) between each reflective structure and the corresponding organic emissive structure, such that the first region M1and the second region M2of each reflective structure are not directly in contact with the corresponding organic emissive structure. Further,FIG. 5Cschematically shows a sectional view of the OLED display panel inFIG. 5A, in which the organic emissive structure of the green (G) pixel shifts and partially overlaps with the organic emissive structure of the red (R) pixel. As shown inFIG. 5C, the organic emissive structure540G of the green (G) pixel shifts leftward and partially overlaps with the organic emissive structure540R of the red (R) pixel, forming the overlapping area560. However, the reflective structure520R is divided into the first region522R and the second region524R, and the second region524R aligns vertically with the overlapping area560. Since the second reflective ratio of the second region524R is less than 100% (in comparison to the 100% reflective ratio of the first region522R), the reflective ratio of the R pixel corresponding to the second region524R will be less than the reflective ratio of the R pixel corresponding to the first region522R, thus reducing the unwanted yellow pattern.

In the embodiment as shown inFIG. 5B, the first area ratio of the first region M1is 80% of the total area of the reflective structure520, and the second area ratio of the second region M2is 20% of the total area of the reflective structure520. In certain embodiments, the first area ratio of the first region M1and the second area ratio of the second region M2can be varied. For example, the first area ratio of the first region M1can be X of the total area of the reflective structure520, where X is greater than or equal to 80% and less than or equal to 99%. In this case, the second area ratio of the second region M2is (1-X) of the total area of the reflective structure520.

FIGS. 6A, 6B and 6Cschematically show multiple examples of the organic emissive structures and the reflective structures of two adjacent pixels of an OLED display panel according to certain embodiments of the present disclosure. Specifically, in each ofFIGS. 6A, 6B and 6C, the two adjacent pixels are respective a R pixel and a G pixel, and the reflective structures620G and620R are substantially square-shaped structures. As shown inFIG. 6A, in the pixel structure600, the organic emissive structures640G and640R do not shift from their intended positions. Although there is a slight overlapping area between the organic emissive structures640G and640R, the overlapping area does not align with any portion of the reflective structures620G and620R.

However, in the case where the organic emissive structure640G shifts leftward, in the pixel structure600′ as shown inFIG. 6B, the overlapping area660may align with a portion of the reflective structure620R, similar to the case as shown inFIG. 4C, and causing unwanted yellow pattern as shown inFIG. 3B.

In order to solve the unwanted mixing color patterns caused by the shift of the organic emissive structures, in the pixel structure600″ as shown inFIG. 6C, the reflective structure620R has a first region622R and a second region624R. Thus, in the case where the organic emissive structure640G shift leftward, the overlapping area660may align with the second region624R of the reflective structure620R, similar to the case as shown inFIG. 5C. Since the second reflective ratio of the second region624R is less than 100% (in comparison to the 100% reflective ratio of the first region622R), the reflective ratio of the R pixel corresponding to the second region624R will be less than the reflective ratio of the R pixel corresponding to the first region622R, thus reducing the unwanted yellow pattern.

In the embodiments as shown inFIG. 6C, the reflective structures620R and620G are square-shaped, and the first region is surrounded by the second region. In certain embodiments, however, the shape of the reflective structures and arrangement of the first and second regions may vary. For example, the shape of the reflective structures may be changed based on the shape of the pixels. Further, the arrangement of the first and second regions may be adjusted based on the occurrences and/or the frequency of the shifts of the organic emissive structures. In certain embodiments, if the shifts of the organic emissive structures occur more frequently in a specific direction, the second region may be arranged along this specific direction, instead of surrounding the first region.

FIG. 7schematically shows a plurality of reflective structures according to certain embodiments of the present disclosure. Specifically, the reflective structure710is identical or similar to each of the reflective structures620R and620G. In contrast, the other reflective structures720-790are modified to have different shapes and/or different arrangements of the first region M1and the second region M2. In particular, the reflective structure720remains square-shaped, but the arrangement of the first region M1and the second region M2is changed to a vertical arrangement, in which the first region M1divides the second region M2into an upper area and a lower area separate from each other. The reflective structure730remains square-shaped, but the arrangement of the first region M1and the second region M2is changed to a diagonal arrangement, in which the first region M1divides the second region M2into an upper-left area and a lower-right area separate from each other. The reflective structure740is diamond-shaped, and the first region M1and the second region M2are arranged such that the first region M1is surrounded by the second region M2. The reflective structure750is also diamond-shaped, and the arrangement of the first region M1and the second region M2is changed to a horizontal arrangement, in which the first region M1divides the second region M2into a left area and a right area separate from each other. The reflective structure760is also diamond-shaped, and the arrangement of the first region M1and the second region M2is changed to a slant arrangement, in which the first region M1divides the second region M2into an upper-left area and a lower-right area separate from each other. The reflective structure770is hexagonal-shaped, and the first region M1and the second region M2are arranged such that the first region M1is surrounded by the second region M2. The reflective structure780is also hexagonal-shaped, and the arrangement of the first region M1and the second region M2is changed to a horizontal arrangement, in which the first region M1divides the second region M2into a left area and a right area separate from each other. The reflective structure790is also hexagonal-shaped, and the arrangement of the first region M1and the second region M2is changed to a vertical arrangement, in which the first region M1divides the second region M2into an upper area and a lower area separate from each other. In certain embodiments, the reflective structure may also be in other shapes, such as a rectangular shape, or any other shape.

As discussed above, in each of the reflective structures, the first reflective ratio of the first region M1is greater than the second reflective ratio of the second region M2, such that the first reflective ratio of the respective pixel corresponding to the first region is greater than the second reflective ratio of the respective pixel corresponding to the second region. In certain embodiments, the first region M1and the second region M2may be formed with a same reflective material and have different thicknesses such that the reflective ratios of the first region M1and the second region M2vary due to the different thicknesses. Generally, the reflective ratio of the reflective structure increases when the thickness of the reflective structure increases. In this case, a first thickness of the first region M1may be greater than a second thickness of the second region M2, such that the first reflective ratio of the first region M1is greater than the second reflective ratio of the second region M2. In certain embodiments, the reflective material may be a metal material selected from Ag, Al, Mg and Mo.

In certain embodiments, the first region M1and the second region M2may be formed with different reflective materials and have a same thickness. Since different reflective materials may have different reflective ratios, the material being used in the first region M1may be a material with a higher reflective ratio, such that the first reflective ratio of the first region M1is greater than the second reflective ratio of the second region M2. In certain embodiments, the reflective materials may be a metal material selected from Ag, Al, Mg and Mo.

FIG. 8shows the reflective ratio to thickness relationships of different reflective materials as the reflective structure in a blue (B) pixel according to certain embodiments of the present disclosure. Correspondingly, Table 1 shows a list of examples of the ratios in different arrangement of the reflective structures in the blue (B) pixels according to certain embodiments of the disclosure. It should be noted that the ratios of the reflective structures in the pixels of the same color should be the same. For example, the ratios of the reflective structures in the blue (B) pixels are the same. However, for the pixels of different colors, the ratios of the reflective structures may be the same or may be different. For example, the ratios of the reflective structures in the blue (B) pixels may be different from the ratios of the reflective structures in the green (G) pixels.

Specifically, in Example 1, the reflective structure is not divided into multiple regions (thus the area ratio of M1being 100%), which is similar to the structure as shown inFIG. 4A. In Examples 2 and 3, the reflective structure is divided into two regions M1and M2, where the first area ratio of the first region M1is 80% and the second area ratio of the second region M2is 20%. In all cases, the reflective material used for the first region M1is Ag, and the thickness of the first region M1is 100 nm. Thus, the reflective ratio of the first region M1is 100% (point A inFIG. 8). Accordingly, in Example 1, the total reflective ratio (which is the sum of the product of the area ratio and the reflective ratio) is 100%. In Example 2, the reflective material used for the second region M2is also Ag, and the thickness of the second region M2is 40 nm. Thus, the reflective ratio of the second region M2is 83% (point B inFIG. 8). Accordingly, in Example 2, the total reflective ratio (which is the sum of the product of the area ratio and the reflective ratio) is 96.6% (=80%*100%+20%*83%). In Example 3, the reflective material used for the second region M2is Mg (which is less reflective), and the thickness of the second region M2remains 100 nm. Thus, the reflective ratio of the second region M2is 65% (point C inFIG. 8). Accordingly, in Example 3, the total reflective ratio (which is the sum of the product of the area ratio and the reflective ratio) is 93% (=80%*100%+20%*65%).

Further, as shown inFIG. 8, for each of the reflective materials, the reflective ratio thereof reaches a stabilized value when the thickness of each reflective material is over 100 nm, and a substantial drop of the reflective ratio thereof can be observed when the thickness of each reflective material is under 40 nm (particularly in the case of Ag, Mg and Mo). Therefore, in certain embodiments, the thickness of the first region M1is set to be less than or equal to 100 nm and greater than or equal to 40 nm, such that each reflective structure can be relatively thin without sacrificing the reflective ratio thereof,

It should be noted that, in a hypothetical example, the material used for the second region M2can be a non-reflective material, which has the reflective ratio of 0%. In this case, the total reflective ratio (which is the sum of the product of the area ratio and the reflective ratio) is 80% (=80%*100%+20%*0%). Since the reflective material being used for the second region M2is generally a reflective material having the reflective ratio greater than 0%, the total reflective ratio should be generally greater than 80%. In certain embodiments, for each of the reflective structures, the difference between the first reflective ratio of the first region M1and the second reflective ratio of the second region M2should be greater than or equal to 1%, such that human eyes can recognize the difference thereof.

Further, in each of the examples as shown in Table 1, the reflective ratio of the second region M2is less than 100%. In certain embodiments, the reflective ratio of the second region M2should be no greater than 99% (i.e., at least 1% less than the reflective ratio of the first region M1), such that the reflective ratios of the first region M1and second region M2is differentiated for human eyes to distinguish the corresponding differences in the emission luminance thereof.

FIG. 9shows the absolute reflective ratio to light wavelength relationships of Ag as the reflective material of the reflective structure with different thickness according to certain embodiments of the present disclosure. Correspondingly, Table 2 shows a list of the ratios of the structure in Example 1 (M1100% area ratio) in a blue (B) pixel (460 nm wavelength), where the reflective material is Ag with different thickness according to certain embodiments of the disclosure. As shown inFIG. 9, when the thickness of the Ag layer increases, the absolute reflective ratio R % of the reflective structure correspondingly increases. It should be noted that a difference exists in the absolute (actual) reflective ratio and the relative reflective ratio.

In the examples as shown in Table 1 and Table 2, the absolute reflective ratio of Ag refers to the actual reflective ratio of Ag in the specific thickness, and the relative reflective ratio is a normalized ratio calculated using the absolute reflective ratio (i.e., the actual reflective ratio) of Ag having a thickness of 100 nm as the basis. Specifically, the relative reflective ratio of the first region M1is 100% when the thickness of the first region M1is set as 100 nm. In certain embodiments, the thickness of each of the reflective structures is set to be 80 nm, such that the relative reflective ratio (99%) and the corresponding absolute reflective ratio (92%) remain relatively high. In certain embodiments, the thickness of each of the reflective structures may be less than 80 nm. As discussed above, in certain embodiments, the thickness of the first region M1can be set to be less than or equal to 100 nm and greater than or equal to 40 nm.

In the embodiments as discussed above, the reflective structure has two regions, including a first region M1and M2. In certain embodiments, additional regions may be added such that the reflective structure has more than two regions. For example,FIG. 10schematically shows a top view of a reflective structure having three regions according to certain embodiments of the present disclosure. As shown inFIG. 10, the reflective structure1000is substantively a square-shaped structure, which is divided into three regions, including a first region (M1)1022, a second region (M2)1024surrounding the first region M1, and a third region (M3)1026between the first region M1and the second region M2. The area ratios of the first region M1, the second region M2and the third region M3may be corresponding adjusted. In certain embodiments, a third reflective ratio of the reflective structure1000corresponding to the third region M3is greater than the second reflective ratio of the reflective structure1000corresponding to the second region M2and less than the first reflective ratio of the reflective structure1000corresponding to the first region M1. In certain embodiments, the reflective structure can be divided into more than three regions, and details of these embodiments are not elaborated herein.

In certain embodiments, the OLED display panel as discussed may be used to achieve higher resolution. For example, the resolution of the OLED display panel may be greater than 600 ppi. Further, the OLED display panel as discussed may be utilized in any device that requires higher resolution, such as a VR device.