Organic light-emitting panel, manufacturing method thereof, and organic display device

A pixel in the panel includes sub-pixels 100a, 100b, and 100c. Bank 105a separates organic light-emitting layer of sub-pixel 100a and organic light-emitting layer of a sub-pixel of a pixel that is adjacent to sub-pixel 100a. Bank 105d separates organic light-emitting layer of sub-pixel 100c and organic light-emitting layer of a sub-pixel of a pixel that is adjacent to sub-pixel 100c. Bank 105b separates organic light-emitting layer of sub-pixel 100a and organic light-emitting layer of sub-pixel 100b. Bank 105c separates organic light-emitting layer of sub-pixel 100b and organic light-emitting layer of sub-pixel 100c. Inclination angle θcb of sidewall 105cb of bank 105c located on the side of sub-pixel 100c is set to be larger than other inclination angles θaa, θba, θbb, θcc and θdc.

TECHNICAL FIELD

The present invention relates an organic light-emitting panel, a manufacturing method thereof, and an organic display device.

BACKGROUND ART

In recent years, progress has been made in the research and development of display devices that use the phenomenon of electroluminescence occurring in organic material. Each light-emitting cell of such a display device is composed of an anode and a cathode with an organic light-emitting layer therebetween. When the display device is driven, holes are injected through the anode, electrons are injected through the cathode, and the holes and electrons recombine within the organic light-emitting layer, thereby emitting the light.

Banks composed of insulating material partition the organic light-emitting layer into light-emitting cells. The organic light-emitting layer is formed by dripping ink, which includes an organic light-emitting material, into each region separated by the banks and drying the ink.

Meanwhile, a problem with the organic light-emitting layer formed in this way is that it is difficult for the layer to have a uniform film thickness.

As one example of technologies for evening out the film thickness of the organic light-emitting layer, Patent Literature 1 discloses providing a convexity on the inner sidewall of the bank in order to control the pinning location of the ink. In other words, according to the technology of Patent Literature 1, the pinning location of the ink dripped in one light-emitting cell can be set to the convexity. With this technology, it is possible to secure a uniform film thickness to a certain degree.

CITATION LIST

Patent Literature

Patent Literature 1: Japanese Patent Application Publication No. 2007-311235

SUMMARY OF INVENTION

Technical Problem

It is considered difficult, however, to use the technology of Patent Literature 1 to detect in advance how the organic light-emitting layer of a display device is uneven in film thickness and, based on the detection results, form a minute convexity for each region or each inner sidewall of the bank to a high degree of precision. Therefore, it is not easy to maintain the organic light-emitting layer at a uniform film thickness over the entire region of the organic light-emitting panel.

It is an object of the present invention to solve the above problems by providing a display device, and a manufacturing method thereof, that has a uniform film thickness in the organic light-emitting layer across the entire panel and has an even luminance within the panel.

Solution to Problem

In order to solve the above problems, an organic light-emitting panel according to an aspect of the present invention has the following structure.

The organic light-emitting panel according to an aspect of the present invention comprises: an array of a plurality of pixels; a plurality of light-emitting cells which, provided in each pixel and arranged in an alignment, emit light of different colors, each light-emitting cell including an underlying layer, a first electrode provided in the underlying layer, an organic light-emitting layer, and a second electrode formed on an opposite side of the organic light-emitting layer from the underlying layer; and a plurality of banks which, formed above the underlying layer, define each light-emitting cell by separating the light-emitting cells one from another, the plurality of pixels including a pixel that is structured such that two inner sidewalls, which face each other in two adjacent banks defining a predetermined light-emitting cell among the plurality of light-emitting cells, have different inclination angles.

Advantageous Effects of Invention

The above organic light-emitting panel according to an aspect of the present invention is structured such that two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell, have different inclination angles. This structure makes it possible to adjust the pinning location when ink is dripped during the manufacturing. To be more specific, the larger the inclination angle of a sidewall of a bank is, the higher the pinning location is; and the smaller the inclination angle of a sidewall of a bank is, the lower the pinning location is.

Also, after the ink is dried, the film thickness of the organic light-emitting layer and the inclination angle of the bank sidewall have a reverse relationship. More specifically, the larger the inclination angle of a sidewall of a bank is, the smaller the film thickness of the organic light-emitting layer near the sidewall is, relatively; and the smaller the inclination angle of a sidewall of a bank is, the larger the film thickness of the organic light-emitting layer near the sidewall is, relatively.

Thus, with the structure where two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell, have different inclination angles, the organic light-emitting panel according to an aspect of the present invention can prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics.

DESCRIPTION OF EMBODIMENTS

[Outline of Aspects of Present Invention]

The organic light-emitting panel according to an aspect of the present invention comprises: an array of a plurality of pixels; a plurality of light-emitting cells which, provided in each pixel and arranged in an alignment, emit light of different colors, each light-emitting cell including an underlying layer, a first electrode provided in the underlying layer, an organic light-emitting layer, and a second electrode formed on an opposite side of the organic light-emitting layer from the underlying layer; and a plurality of banks which, formed above the underlying layer, define each light-emitting cell by separating the light-emitting cells one from another, the plurality of pixels including a pixel that is structured such that two inner sidewalls, which face each other in two adjacent banks defining a predetermined light-emitting cell among the plurality of light-emitting cells, have different inclination angles.

The organic light-emitting panel according to an aspect of the present invention is structured such that two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell, have different inclination angles. This structure makes it possible to adjust the pinning location when ink is dripped during the manufacturing. To be more specific, the larger the inclination angle of a sidewall of a bank is, the higher the pinning location is; and the smaller the inclination angle of a sidewall of a bank is, the lower the pinning location is.

Also, after the ink is dried, the film thickness of the organic light-emitting layer and the inclination angle of the bank sidewall have a reverse relationship. More specifically, the larger the inclination angle of a sidewall of a bank is, the smaller the film thickness of the organic light-emitting layer near the sidewall is, relatively; and the smaller the inclination angle of a sidewall of a bank is, the larger the film thickness of the organic light-emitting layer near the sidewall is, relatively.

Thus, with the structure where two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell, have different inclination angles, the organic light-emitting panel according to an aspect of the present invention can prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics.

Note that, in the above description, the “inclination angle” is an angle formed by a side wall of a bank and an upper surface of an underlying layer on which the bank is provided (the underlying layer corresponds to the first electrode, hole injection layer, hole transporting layer, or hole injection transporting layer).

In the above-described organic light-emitting panel, in each of one or more light-emitting cells other than the predetermined light-emitting cell in the pixel that is structured such that the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell have different inclination angles, two inner sidewalls facing each other may have equal inclination angles.

As described above, with the structure where two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell, have different inclination angles, the organic light-emitting panel according to an aspect of the present invention can prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics. In addition, with the above-described structure where, in each of one or more light-emitting cells other than the predetermined light-emitting cell in the pixel, two inner sidewalls facing each other have equal inclination angles, it is possible to prevent the organic light-emitting layer from becoming uneven in film thickness and provide excellent light-emitting characteristics. This makes it possible to obtain excellent light-emitting characteristics in a plurality of pixels.

Note that the term “equal” above does not mean exact mathematical equivalence, but rather takes factors such as dimensional error during manufacturing of the display device into account. Specifically, the term “equal” refers to making the inclination angles equal within the range permitted in practice by the difference in luminous efficiency (uneven luminance) between the light-emitting cells in the central region and peripheral region of the panel.

In the above-described organic light-emitting panel, the plurality of light-emitting cells in each pixel may include a first light-emitting cell located at an end of the alignment, a second light-emitting cell located at a central portion of the alignment, and a third light-emitting cell located at another end of the alignment, the plurality of pixels are arranged to be continuously adjacent to each other, and the plurality of pixels include a pixel that is structured such that two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have equal inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have different inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have equal inclination angles.

With the above-described structure, when a non-light-emitting cell (for example, a bus bar) is not provided between each pair of adjacent pixels and ink is applied to form organic light-emitting layers in an order of the alignment, if the above-described relationships between the inner sidewalls of the banks and the inclination angles are satisfied, the present invention produces an advantageous effect that it is possible to prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics.

In the above-described organic light-emitting panel, the plurality of light-emitting cells in each pixel may include a first light-emitting cell located at an end of the alignment, a second light-emitting cell located at a central portion of the alignment, and a third light-emitting cell located at another end of the alignment, a non-light-emitting cell is provided between each pair of adjacent pixels, a bank is provided between each pair of a pixel and a non-light-emitting cell that are adjacent to each other, the bank separating the pixel from the non-light-emitting cell, and the plurality of pixels include a pixel that is structured such that two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have equal inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have different inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have different inclination angles.

With the above-described structure, when a non-light-emitting cell (for example, a bus bar) is provided between each pair of adjacent pixels and ink is applied to form organic light-emitting layers in an order of the alignment, if the above-described relationships between the inner sidewalls of the banks and the inclination angles are satisfied, the present invention produces an advantageous effect that it is possible to prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics.

In the above-described organic light-emitting panel, the plurality of light-emitting cells in each pixel may include a first light-emitting cell located at an end of the alignment, a second light-emitting cell located at a central portion of the alignment, and a third light-emitting cell located at another end of the alignment, a non-light-emitting cell is provided between each pair of adjacent pixels, a bank is provided between each pair of a pixel and a non-light-emitting cell that are adjacent to each other, the bank separating the pixel from the non-light-emitting cell, and

the plurality of pixels include a pixel that is structured such that two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have different inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have equal inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have different inclination angles.

With the above-described structure, when a non-light-emitting cell (for example, a bus bar) is provided between each pair of adjacent pixels and ink is applied to form organic light-emitting layers at the same time, not in an order of the alignment, if the above-described relationships between the inner sidewalls of the banks and the inclination angles are satisfied, the present invention produces an advantageous effect that it is possible to prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics.

In the above-described organic light-emitting panel, each non-light-emitting cell may include none of the organic light-emitting layers and may include the second electrode and a third electrode that is made of a same material as the first electrodes, the third electrode and the second electrode being electrically connected with each other.

In an organic light-emitting panel, the second electrode, which is provided at a location upper (closer to the light extraction side) than the organic light-emitting layer, is normally made of a light-transmissive material (such as ITO or IZO). However, these materials have high electric resistance. These matters taken into account, the second electrode and the third electrode are connected in the non-light-emitting cell to reduce the electric resistance so that high light-transmissivity can be maintained to prevent a voltage drop from occurring even in a panel of a large size. The third electrode is, for example, a bus bar.

In the above-described organic light-emitting panel, two regions adjacent to the predetermined light-emitting cell may have different ink vapor concentrations when ink is applied to the predetermined light-emitting cell, and among two inner sidewalls facing each other in two adjacent banks defining the predetermined light-emitting cell, a sidewall of a bank, which is located on a side of a region having a lower ink vapor concentration among the two regions, may have a larger inclination angle than a sidewall of a bank, which is located on a side of a region having a higher ink vapor concentration among the two regions.

In the organic light-emitting panel, when ink is applied to a light-emitting cell that is adjacent to two regions having different ink vapor concentrations, the applied ink forming a light-emitting layer has an inherent tendency to be larger in film thickness at an end located on a side of a region having a lower ink vapor concentration than at an end located on a side of a region having a higher ink vapor concentration. Due to this tendency, the light-emitting layer is likely to have an uneven film thickness.

However, with the above-described structure where, a sidewall of a bank, which is located on a side of a region having a lower ink vapor concentration among the two regions, has a larger inclination angle than a sidewall of a bank, which is located on a side of a region having a higher ink vapor concentration among the two regions, the pinning location of the ink in the sidewall of the bank located on the side of the region having a lower ink vapor concentration becomes relatively higher than the pinning location of the ink in the sidewall of the bank located on the side of the region having a higher ink vapor concentration. As a result, it is possible to restrict the film thickness of the organic light-emitting layer in the sidewall of the bank on the side of the region having a lower ink vapor concentration, thereby preventing the uneven film thickness from occurring between two ends of the predetermined light-emitting cell.

Thus, with the above-described structure, it is possible to prevent the organic light-emitting layer in the predetermined light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics in each pixel.

In the above-described organic light-emitting panel, a type of ink corresponding to the predetermined light-emitting cell may be applied to the predetermined light-emitting cell in a state where a type of ink corresponding to one light-emitting cell among two light-emitting cells that are adjacent to the predetermined light-emitting cell in a same pixel, has been applied to the one light-emitting cell and before another type of ink corresponding to the other light-emitting cell among the two light-emitting cells starts to be applied to the other light-emitting cell, and a sidewall of a bank located on a side of the other light-emitting cell may have a larger inclination angle than a sidewall of a bank located on a side of the one light-emitting cell.

In the organic light-emitting panel, when ink is applied to a predetermined light-emitting cell in the state where a type of ink corresponding to one light-emitting cell among two light-emitting cells that are adjacent to the predetermined light-emitting cell in a same pixel, has been applied to the one light-emitting cell and before another type of ink corresponding to the other light-emitting cell among the two light-emitting cells starts to be applied to the other light-emitting cell, the ink vapor concentration is higher on the side of the one light-emitting cell than on the side of the other light-emitting cell. Accordingly, the applied ink forming a light-emitting layer tends to be larger in film thickness at an end located on a side of the other light-emitting cell than at an end located on a side of the one light-emitting cell. Due to this tendency, the light-emitting layer is likely to have an uneven film thickness.

However, with the above-described structure where a sidewall of a bank located on a side of the other light-emitting cell has a larger inclination angle than a sidewall of a bank located on a side of the one light-emitting cell, the pinning location of the ink in the sidewall of the bank located on the side of the other light-emitting cell becomes relatively higher than the pinning location of the ink in the sidewall of the bank located on the side of the one light-emitting cell. As a result, it is possible to restrict the film thickness of the organic light-emitting layer in the sidewall of the bank located on the side of the other light-emitting cell, thereby preventing the uneven film thickness from occurring between two ends of the predetermined light-emitting cell.

Thus, with the above-described structure, it is possible to prevent the organic light-emitting layer in the predetermined light-emitting cell from becoming uneven in film thickness and provide excellent light-emitting characteristics in each pixel.

In the above-described organic light-emitting panel, two regions adjacent to the predetermined light-emitting cell may have different ink vapor concentrations when ink is applied to the predetermined light-emitting cell, and two regions adjacent to a light-emitting cell, which is different from the predetermined light-emitting cell, may have equal ink vapor concentrations when ink is applied to the light-emitting cell.

In the above-described organic light-emitting panel, the plurality of light-emitting cells provided in each pixel may include a first light-emitting cell located at an end of the alignment, a second light-emitting cell located at a central portion of the alignment, and a third light-emitting cell located at another end of the alignment, each organic light-emitting layer being formed by applying, for each pixel, three types of ink, which correspond one-to-one to the different colors of light, respectively to the three light-emitting cells in an order of the first light-emitting cell, the second light-emitting cell and the third light-emitting cell, the plurality of pixels are arranged to be continuously adjacent to each other, and in each pixel, two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have equal inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have different inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have equal inclination angles.

The above structure exerts an effect on the structure where a non-light-emitting cell is not provided between each pair of adjacent pixels and ink is applied in the order of the first light-emitting cell, the second light-emitting cell and the third light-emitting cell in each pixel. That is to say, in the above structure, two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell to which ink is applied in the first round, have equal inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell to which ink is applied in the second round, have different inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell to which ink is applied in the third round, have equal inclination angles. With this structure, even in the case where different ink vapor concentrations occur because ink is applied to the light-emitting cells in sequence at different timings, it is possible to effectively prevent an uneven film thickness from occurring in the organic light-emitting layer formed in each of the first, second and third light-emitting cells by adjusting the relative pinning locations of the ink in the sidewalls of the banks.

In the above-described organic light-emitting panel, among two inner sidewalls facing each other in two adjacent banks defining the second light-emitting cell, a sidewall of a bank located on a side of the third light-emitting cell may have a larger inclination angle than a sidewall of a bank located on a side of the first light-emitting cell. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the first light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, and the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the first light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, and the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the organic light-emitting panel having the above structure, the inclination angles of the sidewalls of the banks can be set to the following ranges:

(a1) among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, the sidewall of the bank located on the side of the third light-emitting cell has an inclination angle of at least 35 degrees and at most 45 degrees,

(a2) among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, the sidewall of the bank located on the side of the first light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees,

(a3) each of the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees, and

(a4) each of the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees.

In the above-described organic light-emitting panel, the plurality of light-emitting cells provided in each pixel may include a first light-emitting cell located at an end of the alignment, a second light-emitting cell located at a central portion of the alignment, and a third light-emitting cell located at another end of the alignment, each organic light-emitting layer being formed by applying, for each pixel, three types of ink, which correspond one-to-one to the different colors of light, respectively to the three light-emitting cells in an order of the first light-emitting cell, the second light-emitting cell and the third light-emitting cell, a non-light-emitting cell is provided between each pair of adjacent pixels, a bank is provided between each pair of a pixel and a non-light-emitting cell that are adjacent to each other, the bank separating the pixel from the non-light-emitting cell, and in each pixel, two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have equal inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have different inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have different inclination angles.

The above structure exerts an effect on the structure where a non-light-emitting cell is provided between each pair of adjacent pixels and ink is applied in the order of the first light-emitting cell, the second light-emitting cell and the third light-emitting cell in each pixel. That is to say, in the above structure, two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell to which ink is applied in the first round, have equal inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell to which ink is applied in the second round, have different inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell to which ink is applied in the third round, have different inclination angles. With this structure, even in the case where different ink vapor concentrations occur because ink is applied to the light-emitting cells in sequence at different timings, it is possible to effectively prevent an uneven film thickness from occurring in the organic light-emitting layer formed in each of the first, second and third light-emitting cells by adjusting the relative pinning locations of the ink in the sidewalls of the banks.

In the above-described organic light-emitting panel, among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, the sidewall of the bank located on the side of the third light-emitting cell may have a larger inclination angle than the sidewall of the bank located on the side of the first light-emitting cell, and among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, the sidewall of the bank located on the side of the non-light-emitting cell has a larger inclination angle than the sidewall of the bank located on the side of the second light-emitting cell. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the third light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, and the sidewall of the bank located on the side of the non-light-emitting cell among the inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the first light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, and the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the second light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, and the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, may have equal inclination angles.

In the organic light-emitting panel having the above structure, the inclination angles of the sidewalls of the banks can be set to the following ranges:

(b1) among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, the sidewall of the bank located on the side of the third light-emitting cell has an inclination angle of at least 35 degrees and at most 45 degrees,

(b2) among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, the sidewall of the bank located on the side of the non-light-emitting cell has an inclination angle of at least 35 degrees and at most 45 degrees,

(b3) among the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, the sidewall of the bank located on the side of the first light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees,

(b4) among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, the sidewall of the bank located on the side of the second light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees, and

(b5) each of the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees.

In the above-described organic light-emitting panel, the plurality of light-emitting cells provided in each pixel may include a first light-emitting cell located at an end of the alignment, a second light-emitting cell located at a central portion of the alignment, and a third light-emitting cell located at another end of the alignment, each organic light-emitting layer being formed by applying, for each pixel, three types of ink, which correspond one-to-one to the different colors of light, respectively to the three light-emitting cells at the same time, a non-light-emitting cell is provided between each pair of adjacent pixels, a bank is provided between each pair of a pixel and a non-light-emitting cell that are adjacent to each other, the bank separating the pixel from the non-light-emitting cell, and in each pixel, two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have different inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have equal inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have different inclination angles.

The above structure exerts an effect on the structure where a non-light-emitting cell is provided between each pair of adjacent pixels and ink is applied at the same time to the first light-emitting cell, the second light-emitting cell and the third light-emitting cell in each pixel. That is to say, since the ink is applied at the same time and a non-light-emitting cell is provided between each pair of adjacent pixels, two regions located on both sides of the second light-emitting cell (located at the central portion of the alignment) have equal ink vapor concentrations and two regions located on both sides of each of the first and third light-emitting cells have different ink vapor concentrations, when ink is applied to the light-emitting cells. Based on this state of ink vapor concentration distribution, in the above structure, two inner sidewalls, which face each other in two adjacent banks defining the first light-emitting cell, have different inclination angles, two inner sidewalls, which face each other in two adjacent banks defining the second light-emitting cell, have equal inclination angles, and two inner sidewalls, which face each other in two adjacent banks defining the third light-emitting cell, have different inclination angles. With this structure, even in the case where different ink vapor concentrations occur when ink is applied, it is possible to effectively prevent an uneven film thickness from occurring in the organic light-emitting layer formed in each of the first, second and third light-emitting cells by adjusting the relative pinning locations of the ink in the sidewalls of the banks.

In the above-described organic light-emitting panel, among the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, the sidewall of the bank located on the side of the non-light-emitting cell may have a larger inclination angle than the sidewall of the bank located on the side of the second light-emitting cell, and among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, the sidewall of the bank located on the side of the non-light-emitting cell has a larger inclination angle than the sidewall of the bank located on the side of the second light-emitting cell. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the non-light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, and the sidewall of the bank located on the side of the non-light-emitting cell among the inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the second light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, and the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the above-described organic light-emitting panel, the sidewall of the bank located on the side of the second light-emitting cell among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, and the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell, may have equal inclination angles. With this structure, it is possible to prevent an uneven film thickness of the organic light-emitting layer from occurring in each of the first, second and third light-emitting cells.

In the organic light-emitting panel having the above structure, the inclination angles of the sidewalls of the banks can be set to the following ranges:

(c1) among the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, the sidewall of the bank located on the side of the non-light-emitting cell has an inclination angle of at least 35 degrees and at most 45 degrees,

(c2) among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, the sidewall of the bank located on the side of the non-light-emitting cell has an inclination angle of at least 35 degrees and at most 45 degrees,

(c3) among the two inner sidewalls facing each other in the two adjacent banks defining the first light-emitting cell, the sidewall of the bank located on the side of the second light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees,

(c4) among the two inner sidewalls facing each other in the two adjacent banks defining the third light-emitting cell, the sidewall of the bank located on the side of the second light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees, and

(c5) each of the two inner sidewalls facing each other in the two adjacent banks defining the second light-emitting cell has an inclination angle of at least 25 degrees and at most 35 degrees.

In the above-described organic light-emitting panel, each inclination angle may be an angle formed by a side wall of a bank and an upper surface of the underlying layer on which the bank is provided.

In the above-described organic light-emitting panel, the underlying layer may include a TFT layer formed below the first layer, and in the pixel that is structured such that the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell have different inclination angles, the first electrode and the TFT layer may be electrically connected with each other.

An organic display device according to another aspect of the present invention includes any one of the above organic light-emitting panels according to an aspect of the present invention. Therefore, the organic display device according to another aspect of the present invention, as described above, can prevent the organic light-emitting layer in the organic light-emitting panel from becoming uneven in film thickness and provide excellent light-emitting characteristics.

A manufacturing method of an organic light-emitting panel according to a further aspect of the present invention is a manufacturing method of an organic light-emitting panel including an array of a plurality of pixels and the manufacturing method comprises the following steps:

(first step) forming, on a substrate, an underlying layer including a plurality of first electrodes;

(second step) layering a photoresist material on the underlying layer;

(third step) forming, for each pixel, a plurality of openings corresponding to a plurality of light-emitting cells by performing an exposure with a mask laid on the layered photoresist material to form a pattern, and forming a plurality of banks to define each light-emitting cell by separating the light-emitting cells one from another;

(fourth step) forming a plurality of organic light-emitting layers by dripping ink that includes organic light-emitting materials into the plurality of openings corresponding to the plurality of light-emitting cells, and drying the ink; and

(fifth step) forming a second electrode above each organic light-emitting layer.

In the manufacturing method of an organic light-emitting panel according to a further aspect of the present invention, in the third step, at least one pixel among the plurality of pixels is formed such that two inner sidewalls, which face each other in two adjacent banks defining a predetermined light-emitting cell among the plurality of light-emitting cells, have different inclination angles.

With the above manufacturing method of the organic light-emitting panel where two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell among the plurality of light-emitting cells, have different inclination angles, it is possible to adjust the pinning locations of the ink dripped during the manufacturing. To be more specific, the larger the inclination angle of a sidewall of a bank is, the higher the pinning location is; and the smaller the inclination angle of a sidewall of a bank is, the lower the pinning location is.

In the above manufacturing method of an organic light-emitting panel according to a further aspect of the present invention, it is possible to prevent the organic light-emitting layer in each light-emitting cell from becoming uneven in film thickness, based on the relationship that the film thickness of the organic light-emitting layer and the inclination angle of the bank sidewall have a reverse relationship after the ink is dried. It is thus possible to manufacture an organic light-emitting panel with excellent light-emitting characteristics.

In the above manufacturing method of an organic light-emitting panel according to a further aspect of the present invention, in the third step, the at least one pixel may be formed such that two inner sidewalls, which face each other in two adjacent banks defining a light-emitting cell other than the predetermined light-emitting cell, have equal inclination angles.

When the above structure is adopted, two inner sidewalls, which face each other in two adjacent banks defining the predetermined light-emitting cell, are formed to have different inclination angles. It is thus possible to form the organic light-emitting layer having an even film thickness in each light-emitting cell, and manufacture the organic light-emitting panel having excellent light-emitting characteristics, as described above. In addition, with the above-described structure where, in each of one or more light-emitting cells other than the predetermined light-emitting cell in the pixel, two inner sidewalls facing each other have equal inclination angles, it is possible to prevent the organic light-emitting layer from becoming uneven in film thickness and provide excellent light-emitting characteristics. This makes it possible to manufacture an organic light-emitting panel having excellent light-emitting characteristics in all pixels.

Note that the term “equal” above does not mean exact mathematical equivalence, but rather takes factors such as dimensional error during manufacturing of the display device into account. Specifically, the term “equal” refers to making the inclination angles equal within the range permitted in practice by the difference in luminous efficiency (uneven luminance) between the light-emitting cells in the central region and peripheral region of the panel.

In the above manufacturing method of an organic light-emitting panel according to a further aspect of the present invention, in the third step, when the exposure of the photoresist material is performed, the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell may be formed to have different inclination angles, by causing portions of the photoresist material corresponding to the sidewalls of the banks defining the predetermined light-emitting cell to be exposed to different amounts of light. With the above structure where the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell are formed to have different inclination angles, by causing portions of the photoresist material corresponding to the sidewalls of the banks defining the predetermined light-emitting cell to be exposed to different amounts of light, it is possible to form the organic light-emitting layer having an even film thickness in each light-emitting cell, by adjusting the pinning location. This makes it possible to manufacture an organic light-emitting panel having excellent light-emitting characteristics.

In the above manufacturing method of an organic light-emitting panel according to a further aspect of the present invention, in the third step, when the exposure of the photoresist material is performed, the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell may be formed to have different inclination angles, by using masks that are different in light transmissivity at portions of the photoresist material corresponding to the sidewalls of the banks defining the predetermined light-emitting cell. With the above structure where the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell are formed to have different inclination angles, by causing portions of the photoresist material corresponding to the sidewalls of the banks defining the predetermined light-emitting cell to be exposed to different amounts of light, it is also possible to form the organic light-emitting layer having an even film thickness in each light-emitting cell, by adjusting the pinning location. This makes it possible to manufacture an organic light-emitting panel having excellent light-emitting characteristics.

In the above manufacturing method of an organic light-emitting panel according to a further aspect of the present invention, in the third step, after the photoresist material is exposed and developed, the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell may be formed to have different inclination angles, by additionally performing an exposure process onto a portion of the photoresist material corresponding to one of the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell. The organic display device obtained in this way produces the same advantageous effect as the organic light-emitting panel manufactured by the manufacturing method of the present invention. With the above structure where the two inner sidewalls facing each other in the two adjacent banks defining the predetermined light-emitting cell are formed to have different inclination angles, by causing portions of the photoresist material corresponding to the sidewalls of the banks defining the predetermined light-emitting cell to be exposed to different amounts of light, it is also possible to form the organic light-emitting layer having an even film thickness in each light-emitting cell, by adjusting the pinning location. This makes it possible to manufacture an organic light-emitting panel having excellent light-emitting characteristics.

An organic display device according to a still further aspect of the present invention includes an organic light-emitting panel manufactured by any one of the above-described manufacturing methods of the present invention. The organic display device including the organic light-emitting panel manufactured by the above manufacturing method, as described above, can prevent the organic light-emitting layer in the organic light-emitting panel from becoming uneven in film thickness and provide excellent light-emitting characteristics.

The following describes an example of an embodiment of the present invention with reference to the drawings.

Note that the following Embodiment is simply an example to clearly illustrate a structure of the present invention and the acts and effects thereof. The present invention is in no way limited to the following Embodiment except in its essential characteristic elements.

(Process by which the Embodiment According to the Present Invention was Achieved)

As a result of intense study, the inventor of the present invention discovered the following with regard to the organic light-emitting panel recited in the Background Art and the organic display device provided with the organic light-emitting panel.

Typically, as shown inFIG. 25A, an anode902and an electrode coating layer903covering the anode902are formed on a substrate901, for each of sub-pixels900a,900b, and900c. A hole injection layer904is then formed to cover the entire surface of the electrode coating layer903and the substrate901, and on the hole injection layer904, organic light-emitting layers906a,906b, and906cof different colors are formed one-to-one in sub-pixels900a,900b, and900c. The organic light-emitting layers906a,906b, and906care separated from each other by banks905ato905dformed to stand on the hole injection layer904.

As shown inFIG. 25A, in an organic light-emitting panel of a conventional technology, an uneven film thickness is observed in the organic light-emitting layer906bof the sub-pixel900bthat is located in a central region of the array. Specifically, the following phenomenon occurs. That is to say, the surface level of the organic light-emitting layer906bis higher at location C3in the bank905cthan at location C2in the bank905b. Also, the surface level of the organic light-emitting layer906bis higher than the surface level of the organic light-emitting layer906aat location C1in the bank905b.

Also, as another example, as shown inFIG. 25B, a phenomenon occurs in which the surface levels of the organic light-emitting layers956band956cin the sub-pixels950band950cat locations C12and C14in the banks955cand955dare higher than the surface levels of the organic light-emitting layers956band956cat locations C11and C13in the banks955band955c, respectively. Note that, as shown inFIG. 25B, the surface levels of the organic light-emitting layer956ain the sub-pixel950aat respective locations in the bank955aand the bank955bare approximately the same, and a large amount of unevenness in film thickness is not observed.

After repeated examination of the above phenomenon, the inventor determined that reduction in uniformity of film thickness in the organic light-emitting layer causes a non-uniform vapor concentration distribution during ink drying, as described below. That is to say, as shown inFIG. 26A, suppose a state in which ink9060cfor forming the organic light-emitting layer has been applied in an area between the bank905band the bank905c, and the right-hand side ofFIG. 26Ais lower than the left-hand side in vapor concentration distribution as indicated by the two-dot chain line. In this case, the film thickness in the organic light-emitting layer becomes uneven for the following reasons.

As shown inFIG. 26A, a surface profile L90of ink9060bhas been swollen up in the central region of the sub-pixel immediately after the ink9060bis dripped. When drying the ink, due to the non-uniform vapor concentration distribution as mentioned above, the evaporation rate varies in reverse proportion to the vapor concentration, and therefore it can be theoretically considered that the ink changes to have a surface profile L91.

However, as shown inFIG. 26B, solvent in the ink9061bflows during drying as shown by the dotted-line arrow L92. This is because solvent flows to compensate for solvent that has evaporated (i.e. flows to minimize surface free energy), and along with the flow of the solvent, the solute (organic light-emitting material) also flows. Therefore, as shown inFIG. 26C, if the vapor concentration distribution is not uniform, the organic light-emitting layer906bis formed to have a surface profile L93in which the closer to the right-hand side the layer is, the higher the layer is.

The inventor therefore deduced that, in an organic light-emitting panel, uniformity of film thickness of the organic light-emitting layer decreases due to non-uniformity of vapor concentration distribution during ink drying.

The inventor also discovered technology to vary, within the panel, the pinning location of ink on a bank side wall by varying the inclination angle of the bank side wall, which improves uniformity of film thickness in the organic light-emitting layer.

1. Configuration of Display Device1

The overall structure of the display device1according to the present Embodiment is described with reference toFIG. 1.

As shown inFIG. 1, the display device (organic display device)1includes a display panel unit10and a drive control unit20connected to the display panel unit10. The display panel unit10is an organic light-emitting panel that uses the phenomenon of electroluminescence occurring in organic material and is composed of a plurality of pixels arrayed two-dimensionally in the X-Y plane direction.

The drive control unit20is composed of four drive circuits21-24and a control circuit25.

Note that in an actual display device1, the placement of the drive control unit20with respect to the display panel unit10is not limited in this way.

2. Structure of Display Panel10

The structure of the display panel10is described with reference toFIG. 2. Note that, as an example, the display panel10in the present Embodiment is a top emission type organic light-emitting panel including a plurality of pixels arranged in a matrix, each pixel including sub-pixels that are each provided with an organic light-emitting layer having a luminescent color of either red (R), green (G), or blue (B).FIG. 2depicts one sub-pixel100in a pixel.

As shown inFIG. 2, in the display panel10, anodes102are formed above a TFT substrate (hereinafter simply referred to as a “substrate”)101in one-to-one correspondence with the sub-pixels300a,300band300c, and on each of the anodes102, an electrode coating layer103is formed, and a hole injection transporting layer104is layered on the electrode coating layers103.

Above the hole injection transporting layer104, banks105, made of insulating material, are provided to stand to separate the sub-pixels100from each other. An organic light-emitting layer106is formed in the region in each sub-pixel100separated by the banks105, and an electron injection layer107, cathode108, and passivation layer109are layered above the organic light-emitting layer106in this order.

The anode102is composed of a single layer or of a laminate of a plurality of layers, either being made of a conductive material, such as aluminum (Al), alloy including Al, silver (Ag), alloy of silver, palladium, and copper (APC), alloy of silver, rubidium, and gold (ARA), alloy of molybdenum and chromium (MoCr), alloy of nickel and chromium (NiCr), etc. Note that in the case of a top emission type panel such as the panel in the Embodiment, it is preferable that the anode102be made of a highly reflective material.

The electrode coating layer103is made of, for example, indium tin oxide (ITO) and covers at least a part of the top surface the anode102in the Z axis direction.

The hole injection transporting layer104is a layer formed from an oxide of a metal such as silver (Ag), molybdenum (Mo), chromium (Cr), vanadium (V), tungsten (W), nickel (Ni), or iridium (Ir), or formed from a conductive polymer material, such as PEDOT (a mixture of polythiophene and polystyrene sulfonate). The hole injection transporting layer104formed from such a metal oxide, among the above materials, has the function of assisting with generation of holes and injecting and transporting the holes stably into the organic light-emitting layer106. The hole injection transporting layer104has a high work function.

When the hole injection transporting layer104is made of an oxide of a transition metal, a plurality of levels can be occupied since there are a plurality of oxidation numbers. This makes hole injection easy and allows for reduction of driving voltage.

The banks105are made of an organic material such as resin and have insulating properties. Examples of the organic material used to form the banks105include acrylic resin, polyimide resin, novolac-type phenolic resin, etc. It is also preferable that the banks105have organic solvent resistance.

Furthermore, since the banks105are etched and baked when formed, it is preferable that the banks be made of a highly resistant material that will not change in shape or quality during the etching and baking processes. To provide the banks with liquid repellency, the sidewalls can be fluoridated.

Note that as the insulating material used in forming the banks105, any liquid repellent material with a resistivity of 105Ω·cm can be used, starting with the above materials. Using a material with a resistivity of less than 105Ω·cm leads to production of leak current between the anode102and the cathode108, or between adjacent sub-pixels100, which causes a variety of problems such as increased power consumption.

Furthermore, if a hydrophilic material is used to form the banks105, the difference in affinity/liquid repellency between the sidewall of the banks105and the surface of the hole injection transporting layer104becomes small, and it thus becomes difficult to selectively maintain the ink, which includes an organic substance for forming the organic light-emitting layer106, at the opening of the banks105.

The structure of the banks105need not be a single layer as shown inFIG. 2, but may adopt a multi-layered structure composed of two or more layers. In such a case, the above materials may be combined for each layer, or layers may alternate between non-organic and organic material.

The organic light-emitting layer106has a function to emit light when an excitation state is produced by the recombination of holes injected through the anode102with electrons injected through the cathode108. The material used to form the organic light-emitting layer106needs to be a light-emitting organic material, a film of which can be formed by wet printing.

The electron injection layer107has a function to transport electrons injected through the cathode108to the organic light-emitting layer106and is preferably made of, for example, barium, phthalocyanine, lithium fluoride, or a combination thereof.

The cathode108is made of, for example, ITO, indium zinc oxide (IZO), etc. When the display panel10is a top-emission type, it is preferable that the cathode108be made of a light-transmissive material. It is preferable that the light transmissivity be 80% or greater.

The material used to form the cathode108may be, in addition to the above materials, for example, an alkali metal, alkali earth metal, or a laminate structure having, in the following order, a layer that includes a halide of an alkali metal or alkali earth metal and a layer that includes silver. The layer that includes silver may be made of silver alone, or from a silver alloy. Also, in order to increase light extraction efficiency, a highly-transparent refraction index adjustment layer may be provided above the layer that includes silver.

The passivation layer109has a function to control the organic light-emitting layer106or other layers from being exposed to water or air and is made of, for example, silicon nitride (SiN), silicon oxynitride (SiON) etc. When the display panel10is a top-emission type, it is preferable that the passivation layer109be made of a light-transmissive material.

3. Structure of Banks105

As shown inFIG. 3, in the display panel10of the present Embodiment, the banks105are arranged in lines, as one example. More specifically, the banks105each extend along the Y axis and separate the adjacent sub-pixels100in the X axis direction. The sub-pixels100are formed so that each of the regions separated by the banks105in each pixel emits a different color. For example, one pixel is composed of three sub-pixels that emit light of red (R), green (G), and blue (B), respectively.

4. Structure of Banks105in Each Region

The structure of the banks105in each region is described with reference toFIG. 4. Note thatFIG. 4is a schematic cross-sectional view taken along line A-A′ passing through the display panel10inFIG. 1, and schematically illustrating some parts thereof.

As shown inFIG. 4, sub-pixels100a,100b, and100care arranged continuously in this order from left to right along the X axis direction. Note that in the display panel10of the present embodiment, the sub-pixels are arranged to be continuously adjacent to each other.

The sub-pixel100ais defined by banks105aand105b; the sub-pixel100bis defined by banks105band105c; and the sub-pixel100cis defined by banks105cand105d. Sidewalls105aa,105ba,105bb,105cb,105cc, and105dcof the banks105a,105b,105cand105drespectively form angles θaa, θba, θbb, θcb, θcc, and θdc with the surface of the hole injection transporting layer104, which is an underlying layer.

In the present Embodiment, the angles θaa, θba, θbb, θcb, θcc, and θdc satisfy the relationships indicated by the following expressions.
θcb>θaa=θba=θbb=θcc=θdc[Expression 1]

Note that in the present Embodiment, it is preferable that the angles θaa, θba, θbb, θcb, θcc, and θdc satisfy the relationships indicated by the above Expression 1 and are set to the following ranges.
25°<θaa=θba=θbb=θcc=θdc<35°  [Expression 2]
35°<θcb<45°  [Expression 3]

5. Relationship Between Inclination Angle θ of Sidewall of Banks105and Film Thickness of Organic Light-Emitting Layer106

The relationship between the inclination angles θ of the sidewalls of the banks105and the film thickness of the organic light-emitting layer106is described with reference toFIGS. 5 and 6. Note thatFIG. 5is a schematic rendering of the structure of a sub-pixel.

As shown inFIG. 5A, the inclination angle of the sidewall of bank105x(the angle formed between the sidewall and the surface of the hole injection transporting layer104) is represented by angle θx, and as shown inFIG. 5B, the inclination angle of the sidewall of bank105y(the angle formed between the sidewall and the surface of the hole injection transporting layer104) is represented by angle θy. Here, the angles θx and θy satisfy the following relationship.
θy>θx  [Expression 4]

When ink1060xand ink1060y, which include an organic light-emitting material, are each dripped into the openings defined by the banks105xand105y, respectively, the pinning locations Px and Py respectively have heights Hx and Hy that satisfy the following relationship.
Hy>Hx  [Expression 5]

As shown inFIG. 5C, after drying the ink106θx, the height Hx of the pinning location Px is relatively low, which causes the organic light-emitting layer106xto swell at the central portion of the sub-pixel to a film thickness of Tx.

On the other hand, as shown inFIG. 5D, after drying the ink1060y, the height Hy of the pinning location Py is relatively high, which causes the organic light-emitting layer106yto sag at the central portion of the sub-pixel to a film thickness of Ty.

The thicknesses Tx and Ty satisfy the following relationship.
Tx>Ty  [Expression 6]

FIG. 6summarizes the above relationships. As shown inFIG. 6, as the inclination angle (taper angle) θ of the bank105grows smaller, the pinning height H lowers, and as a result, the film thickness T of the organic light-emitting layer106becomes thicker. Conversely, as the inclination angle (taper angle) θ of the bank105grows larger, the pinning height H becomes higher, and as a result, the film thickness T of the organic light-emitting layer106becomes thinner.

Based on the above factors, five samples were created and evaluated.FIGS. 7 and 8show the results.

As shown inFIGS. 7 and 8, as compared to the distribution of film thickness of sample 2, the pinning location is higher in samples 3 and 4, which have a larger taper angle. Note that inFIGS. 7 and 8, the horizontal axis represents the horizontal direction, and the vertical axis represents the direction of height.

In sample 5, however, in which the bank has a taper angle (inclination angle) of 50°, the film thickness is less uniform than in sample 2.

6. Manufacturing Method of Display Panel10

The following describes the characteristic processes of the manufacturing method of the display panel10according to the present Embodiment with reference toFIGS. 9 and 10. Note that with regard to the manufacturing processes that are omitted in the following description, any of the variety of processes suggested by conventional technologies may be used.

First, as shown inFIG. 9A, above the substrate101in the direction of the Z axis, anodes102and electrode coating layers103are layered in this order in regions in which sub-pixels1000a,1000b, and1000care to be formed. Furthermore, A hole injection transporting layer104is then layered thereon so as to cover the entire surface. The anodes102is formed, for example, by first forming a thin film made of Al or Al alloy or a thin Ag film by the sputtering method or vacuum deposition method and then patterning the thin Ag film by the photolithography method.

The electrode coating layers103is formed, for example, by forming a thin ITO film on the surface of the anodes102using a method such as the sputtering method and then patterning the thin ITO film by a method such as photolithography. To form the hole injection transporting layer104, first a metal film is formed on the surface of the substrate101, including the surface of the electrode coating layer103, by a method such as the sputtering method. Subsequently, the metal film is oxidized to form the hole injection transporting layer104.

Next, as shown inFIG. 9B, the spin coat method, for example, is used to form a bank material layer1050so as to cover the top of the hole injection transporting layer104. A photoresist material is used to form the bank material layer1050. Specifically, as described above, an organic material having insulating properties such as acrylic resin, polyimide resin, novolac-type phenolic resin, etc. can be used.

Subsequently, as shown inFIG. 9C, a mask501is placed above the bank material layer1050, the mask501having openings501a,501b,501c, and501dat the locations for forming the banks. In this state, exposure is performed via the openings501a,501b,501c, and501dof the mask501.

Note that, as shown inFIG. 9C, in the mask501, a width Wa of the opening501alocated on the left-hand side of a region1000ain which a sub-pixel is to be formed (hereinafter, such a region is referred to as “planned sub-pixel formation region”), is defined by points Pa1and Pa2positioned at the foots of the sidewalls105aa, . . . of the bank105athat is to be formed (seeFIG. 4).

On the other hand, a width Wc1of the opening501clocated between the planned sub-pixel formation regions1000band1000cis defined by a point Pc1being at the upper edge of the sidewall105cbof the bank105cthat is to be formed (seeFIG. 4) and a point Pc2being at the foot of the sidewall105ccof the bank105cthat is to be formed (seeFIG. 4).

Next, as shown inFIG. 10A, a mask502is placed above the bank material layer1050, the mask502having opening502cat the location corresponding to the sidewall105cbof the bank105c(seeFIG. 4). In this state, the second exposure is performed via the opening502cof the mask502.

Note that, as shown inFIG. 10A, in the mask502, a width Wc2of the opening502cis defined by points Pc3and Pc1being at the foot and the upper edge of the sidewall105cbof the bank105cthat is to be formed.

Next, the development and baking are performed to form the banks105a,105b,105e, and105das shown inFIG. 10B. As described above, the sidewall105cbof the bank105con the planned sub-pixel formation region1000bside is larger than the sidewalls105aa,105ba,105bb, and105dcof the banks105a,105band105dand the sidewall105ccof the bank105con the planned sub-pixel formation region1000cside.

After this, as shown inFIG. 10C, ink1060aincluding an organic light-emitting material is applied to an opening (the planned sub-pixel formation region1000a) defined by the banks105aand105bby the inkjet method or the like.

Subsequently, as shown inFIG. 11A, ink1060bincluding an organic light-emitting material is applied to an opening (the planned sub-pixel formation region1000b) defined by the banks105band105cby the inkjet method or the like. Here, since, as described above, the inclination angle of the sidewall105cbof the bank105cis set to be larger than the inclination angles of the other sidewalls, the pinning location Qcb of the ink1060bin the sidewall105cbof the bank105cbecomes higher in position than the other pinning locations Qaa, Qba, and Qbb.

Subsequently, as shown inFIG. 11B, ink1060cincluding an organic light-emitting material is applied to an opening (the planned sub-pixel formation region1000c) defined by the banks105cand105dby the inkjet method or the like. Here, since ink has already been applied to the planned sub-pixel formation region adjacent, on the right-hand side, to the bank105d, two ends of the applied ink1060cin the X axis direction have the same ink vapor concentration, and the organic light-emitting layer has even film thickness without adjustment of the inclination angles of the sidewalls of the banks. This is clear from the above.

Note that, although not illustrated, subsequently the ink is dried, and the electron injection layer107, cathode108, passivation layer109, etc, are layered in this order to form the display panel10.

7. Ink Applying Process and Drying Process

The following describes the relationships between the ink applying process and the ink drying process with reference toFIGS. 12A and 12B.

As illustrated inFIG. 12A, in the present embodiment, firstly red ink (the ink1060a) is applied (step S1), then green ink (the ink1060b) is applied (step S2), and blue ink (the ink1060c) is applied (step S3). After this, ink drying process is performed to dry all the applied inks at once (step S4).

As an alternative to the above method, as illustrated inFIG. 12B, the following processes may be performed in sequence in the stated order: applying red ink (the ink1060a) (step S11) and drying the applied red ink (step S12); applying green ink (the ink1060b) (step S21) and drying the applied green ink (step S22); and applying blue ink (the ink1060c) (step S31) and drying the applied blue ink (step S32). In this case, the relationships in inclination angle among the side walls105aa,105ba,105bb,105cb,105cc, and105dcof the banks105a,105b,105c, and105dmay be the same as those described above. This structure also can restrict the film thickness of the formed organic light-emitting layer106from becoming uneven.

As shown inFIG. 4, in the display panel10of the display device1according to the present Embodiment, inclination angle θcb of the sidewall105cbof the bank105cpositioned on the sub-pixel100cside is set larger than the inclination angles θaa, θba, θbb, θcc, and θdc of other sidewalls105aa,105ba,105bb,105cc, and105dc. As a result, as shown inFIG. 11A, when the ink1060bis applied in the planned sub-pixel formation region1000b, the pinning location Qcb is higher in position than the other pinning locations Qaa, Qba, and Qbb.

On the other hand, the inclination angles θaa, θba, θbb, θcc, and θdc of the other sidewalls105aa,105ba,105bb,105cc, and105dcare equal.

This enables sub-pixels100a,100b, and100cto have a uniform film thickness in the organic light-emitting layer106of the display panel10after drying, which produces an advantageous effect of having little luminance unevenness.

Note that, by using the manufacturing method of the display device1in the present Embodiment, which has been described with reference toFIGS. 9,10, and11, the display device1having the above advantageous effect can be manufactured.

Also, the term “equal” does not necessarily mean that the targets are completely equal with each other in numerical value, but includes, for example, a measurement error in manufacturing of the display device1. More specifically, it is suggested that, in the display panel10, the inclination angles are recognized as being equal as far as the difference in luminous efficiency (luminance unevenness) between sub-pixels100a,100b, and100c, which correspond to the inclination angles, fails in an acceptable range.

Next, with reference toFIG. 13, Modification 1 of the manufacturing method of the display device1is described.FIG. 13illustrates processes corresponding to processes illustrated inFIGS. 9C to 10A.

As shown inFIG. 13, first a bank material layer1050is formed to cover the hole injection transporting layer104, and then a mask503is placed above the bank material layer1050. The mask503is provided with light transmissive portions503a,503b,503c1,503c2, and503d. The light transmissive portions503a,503b,503c1,503c2, and503dare provided at locations corresponding to portions in which the banks105a,105b,105c, and105dare to be formed.

In the manufacturing method of the display device1in Modification 1, width Wa of the light transmissive portion503a, which corresponds to the left-hand side of the planned sub-pixel formation region1000a, is defined by points Pa1and Pa2at the feet of the sidewalls105aa, . . . of the bank105a(seeFIG. 4) that is to be formed.

On the other hand, width Wc2of the light transmissive portion503c1, which corresponds to a region between the planned sub-pixel formation regions1000band1000c, is defined by points Pc2and Pc1that are respectively positioned at the foot and upper edge of the bank105cto be formed (seeFIG. 4). Also, the light transmissive portion503c2is defined by points Pc3and Pc1that are respectively positioned at the foot and upper edge of the sidewall105cbof the bank105cto be formed (seeFIG. 4).

The mask503is made from a half-tone or the like, and the light transmissive portions503a,503b,503c1, and503ddiffer from the light transmissive portion503c2in light transmissivity. More specifically, the light transmissive portion503c2is larger than the light transmissive portions503a,503b,503c1, and503din light transmissivity.

In the state where the mask503having the above structure is set in place, the exposure and development, and then baking are performed to form the banks105a,105b,105c, and105das shown inFIG. 10B. That is to say, sidewalls having larger inclination angles are formed at locations which are exposed to light via the light transmissive portion503c2having a larger light transmissivity than the light transmissive portions503a,503b,503c1, and503d, in accordance with the relationship indicated by the above-described Expression 1.

Note that subsequent processes are the same as those in the above Embodiment.

The display device1can be manufactured by the above manufacturing method as well.

Next, with reference toFIGS. 14A to 15B, Modification 2 of the manufacturing method of the display device1is described.FIGS. 14A to 15Billustrate processes corresponding to the processes illustrated inFIGS. 9C to 10B.

As shown inFIG. 14A, first a bank material layer1050is formed to cover the hole injection transporting layer104, and then a mask504is placed above the bank material layer1050. The mask504has openings504a,504b,504c, and504dcorresponding to the portions at which banks105are to be formed.

The openings504a,504b, and504dare formed to have the same width as the opening501ain the mask501used in the manufacturing method of the above Embodiment.

On the other hand, a width Wc3of the opening504clocated between the planned sub-pixel formation regions1000band1000din correspondence with the bank105cthat is to be formed (seeFIG. 4) is set to be larger than a width that is defined by points Pc3and Pc2being at the feet of the bank105cthat is to be formed (seeFIG. 4), as indicated by the two-dot chain line inFIG. 14A. More specifically, the width is made larger at the portions where the inclination angles are to be larger.

In the state where the mask504is set in place as shown inFIG. 14A, the exposure and development in the first round are performed. After this process is performed, as shown inFIG. 14B, bank material layers1051a,1051b,1051c, and1051dremain in the locations corresponding to the openings504a,504b,504c, and504d.

Note that, as shown inFIG. 14B, the inclination angles of the sidewalls in the bank material layers1051a,1051b,1051c, and1051dare uniform after the first exposure and development are performed. In Modification 2, the baking is not performed at this point in time.

As shown inFIG. 15A, a mask505is placed above the bank material layers1051a,1051b,1051c, and1051dafter they are formed. In the mask505, an opening505cis provided only at the location where the inclination angle is to be larger (sidewall105cbof the bank105c) among the locations in the mask505corresponding to the sidewalls of the banks105a,105b,105c, and105dthat are to be formed.

In the state where the mask505is set in place, the exposure and development in the second round are performed, and then the baking is performed to form the banks105a,105b,105c, and105das shown inFIG. 15B.

Subsequently, the display device1can be manufactured by performing the same processes as in the above Embodiment or the like.

[Verification of Manufacturing Method]

Using a concrete example, the shape of the banks after formation was verified for the manufacturing methods of the above Embodiment and Modifications 1 and 2. The results are described with reference toFIGS. 16A and 16B.

As shown inFIG. 16A, the larger the amount of exposure is, the larger the inclination angle of a sidewall of a formed bank is. More specifically, when the exposure and development are performed with 200 mJ of exposure amount, the inclination angle of a sidewall of the formed bank is 23°, whereas when the exposure and development are performed with 300 mJ of exposure amount, the inclination angle of a sidewall of the formed bank is 38°. The results are also shown by the Atomic Force Microscope (AFM) inFIG. 16B.

Furthermore, as shown inFIGS. 16A and 16B, when the exposure and development in the first round is performed with 200 mJ of exposure amount and then the exposure and development in the second round is performed with 100 mJ of exposure amount, the inclination angle of a sidewall of the formed bank is 50°. This corresponds to the manufacturing method of Modification 2 and is considered to be effective in creating a large inclination angle of the bank sidewall.

Note that inFIG. 16B, the horizontal axis represents the horizontal direction, and the vertical axis represents the direction of height.

The following describes an overall structure of the display device in Embodiment 2 with reference toFIGS. 17 and 18.

1. Structure of Display Panel30

As shown inFIG. 17, in the display panel30, as in the display panel10in Embodiment 1, anodes102are formed above a TFT substrate (hereinafter simply referred to as a “substrate”)101in one-to-one correspondence with the sub-pixels300a,300band300c, and on each of the anodes102, an electrode coating layer103is formed, and a hole injection transporting layer104is layered on the electrode coating layers103.

Above the hole injection transporting layer104, banks305a,305b,305c, and305dare formed from insulating material to define the sub-pixels300a,300b, and300c. An organic light-emitting layer is formed in each region of the sub-pixels300a,300b, and300cdefined by the banks305a,305b,305c,305d, and an electron injection layer, a cathode, and a passivation layer are layered above the organic light-emitting layer in this order (illustration of these is omitted inFIG. 17).

In the display panel30of the present embodiment, as is the case with the display panel10in the above-described Embodiment 1, a pixel is composed of three sub-pixels300a,300b, and300c. In addition, in the display panel30of the present embodiment, non-light-emitting cells300dand300eare provided between the pixel and the adjacent pixels on both sides.

More specifically, as illustrated inFIG. 17, each of the non-light-emitting cells300dand300ehas an electrode (bus bar)302, which is made of the same material as the anode102, and an electrode coating layer303covering the electrode302. A hole injection transporting layer104is formed to cover each stack of the layers including the electrode coating layer303. A cathode108(not illustrated) is formed on the hole injection transporting layer104such that the electrode302and the cathode108are electrically connected. Note that the organic light-emitting layer106is not formed in the non-light-emitting cells300dand300e. The above structure makes it possible to lower the electric resistance of the cathode108that is composed of ITO and the like, thereby preventing a voltage drop from occurring.

As illustrated inFIG. 17, in the display panel30of the present embodiment, side walls305aa,305ba,305bb,305cb,305cc, and305dcof the banks305a,305b,305c, and305drespectively form angles θ3aa, θ3ba, θ3bb, θ3cb, θ3cc, and θ3dcwith the surface of the hole injection transporting layer104as an underlying layer.

Here, in the present embodiment, the angles θ3aa, θ3ba, θ3bb, θ3cb, θ3cc, and θ3dcsatisfy the relationships represented by the following expressions.
θ3cb>θ3aa=θ3ba=θ3bb=θ3cc[Expression 7]
θ3dc>θ3aa=θ3ba=θ3bb=θ3cc[Expression 8]

The reason why the inclination angles θ3aa, θ3ba, θ3bb, θ3cb, θ3cc, and θ3dcof the side walls305aa,305ba,305bb,305cb,305cc, and305dcof the banks305a,305b,305c, and305dare defined by the above-described Expressions 7 to 11 is that the non-light-emitting cells300dand300eare provided between a pixel and the adjacent pixels on both sides. Description of this is provided in connection with application of inks3060a,3060b, and3060c.

2. Manufacturing Method of Display Panel30

The following describes the characteristic steps of the manufacturing method of the display panel30according to the present Embodiment with reference toFIGS. 18A to 18C. Note that the steps other than those illustrated inFIGS. 18A to 18Care the same as those of Embodiment 1.

As shown inFIG. 18A, ink3060athat includes an organic light-emitting material is dripped into the opening (planned sub-pixel formation region3000a) defined by the banks305aand305bby the inkjet method or other method. When the ink3060ais applied to the region between the banks305aand305b, ink has not been applied to the left-hand side of the bank305aand the right-hand side of the bank305b, and thus the vapor concentration distribution is substantially uniform.

Following this, as shown inFIG. 18B, ink3060bthat includes an organic light-emitting material is dripped into the opening (planned sub-pixel formation region3000b) defined by the banks305band305cby the inkjet method or other method. Here, as described above, inclination angle θ3cbof the sidewall305cbof the bank305c(seeFIG. 17) is set to satisfy the relationships represented by the above-described Expression 7 (to be relatively larger than the other inclination angles). As a result, the pinning location Q3cbof the ink3060bin the side wall305cbof the bank305cis higher in position than the pinning locations Q3aa, Q3ba, and Q3bb.

Subsequently, as shown inFIG. 18C, ink3060cthat includes an organic light-emitting material is dripped into the opening (planned sub-pixel formation region3000c) defined by the banks305cand305dby the inkjet method or other method. Here, in the present embodiment, the non-light-emitting cell3000d, to which ink is not applied, is present on the right-hand side of the planned sub-pixel formation region3000c. Accordingly, the vapor concentration is lower in the right-hand side of the planned sub-pixel formation region3000cthan in the left-hand side. For this reason, as is the case with the inclination angle θ3cbof the sidewall305cbof the bank305c, the inclination angle θ3dcof the sidewall305dcof the bank305don the planned sub-pixel formation region3000cside (seeFIG. 17) is set to satisfy the relationships represented by the above-described Expressions 7 and 8 (to be relatively larger than the other inclination angles). As a result, the pinning location Q3dcof the ink3060cin the side wall305dcof the bank305d, as well as the pinning location Q3cbof the ink3060b, is higher in position than the other pinning locations.

Note that, although omitted from the drawings, subsequently, the display panel30is formed by layering, in order, the electron injection layer, cathode, passivation layer, etc.

With the above-described structure, even in the case where the non-light-emitting cells300dand300eare provided between a pixel and the adjacent pixels on both sides, it is possible to prevent the organic light-emitting layer from becoming uneven in film thickness in all sub-pixels300a,300b, and300c, and thus it is possible to provide the display panel30having high light transmissivity.

Note that the structures other than those described in the present embodiment are the same as those of Embodiment 1.

The following describes an overall structure of the display device in Embodiment 3 with reference toFIGS. 19 and 20.

1. Structure of Display Panel40

As shown inFIG. 19, in the display panel40, as in the display panel10in Embodiment 1, anodes102are formed above a TFT substrate (hereinafter simply referred to as a “substrate”)101in one-to-one correspondence with the sub-pixels400a,400band400c, and on each of the anodes102, an electrode coating layer103is formed, and a hole injection transporting layer104is layered on the electrode coating layers103.

Above the hole injection transporting layer104, banks405a,405b,405c, and405dare formed from insulating material to define the sub-pixels400a,400b, and400c. An organic light-emitting layer is formed in each region of the sub-pixels400a,400b, and400cdefined by the banks405a,405b,405c,405d, and an electron injection layer, a cathode, and a passivation layer are layered above the organic light-emitting layer in this order (illustration of these is omitted inFIG. 19).

In the display panel40of the present embodiment, as is the case with the display panel30in the above-described Embodiment 2, a pixel is composed of three sub-pixels400a,400b, and400c. In addition, in the display panel40of the present embodiment, non-light-emitting cells400dand400eare provided between the pixel and the adjacent pixels on both sides. With regard to the points described above, the display panel40is the same as the display panel30of Embodiment 2.

A illustrated inFIG. 19, as is the case with Embodiment 2, each of the non-light-emitting cells400dand400ehas an electrode (bus bar)402, which is made of the same material as the anode102, and an electrode coating layer403covering the electrode402. Furthermore, a hole injection transporting layer104is formed to cover each stack of the layers including the electrode coating layer403. A cathode (not illustrated) is formed on the hole injection transporting layer104such that the electrode402and the cathode are electrically connected. Note that the organic light-emitting layer is not formed in the non-light-emitting cells400dand400e. As is the case with Embodiment 2, this structure makes it possible to lower the electric resistance of the cathode that is composed of ITO and the like, thereby preventing a voltage drop from occurring.

As illustrated inFIG. 19, in the display panel40of the present embodiment, side walls405aa,405ba,405bb,405cb,405cc, and405dcof the banks405a,405b,405c, and405drespectively form angles θ4aa, θ4ba, θ4bb, θ4cb, θcc, and θ4dcwith the surface of the hole injection transporting layer104, which is an underlying layer.

Here, in the present embodiment, the angles θ4aa, θ4ba, θ4bb, θ4cb, θcc, and θ4dcsatisfy the relationships represented by the following expressions.
θ4aa>θ4ba=θ4bb=θ4cb=θ4cc[Expression 12]
θ4dc>θ4ba=θ4bb=θ4cb=θ4cc[Expression 13]

The reason why the inclination angles θ4aa, θ4ba, θ4bb, θ4cb, θ4cc, and θ4dcof the side walls405aa,405ba,405bb,405cb,405cc, and405dcof the banks405a,405b,405c, and405dare defined by the above Expressions 12 to 16 is that the non-light-emitting cells400dand400eare provided between a pixel and the adjacent pixels on both sides, and in connection with this, an appropriate method for applying inks4060a,4060b, and4060cis adopted as described below.

2. Manufacturing Method of Display Panel40

The following describes the characteristic steps of the manufacturing method of the display panel40according to the present Embodiment with reference toFIG. 20. Note that the steps other than those illustrated inFIG. 20are the same as those of Embodiment 1.

As shown inFIG. 20, the following inks are applied to the following openings at the same time by the inkjet method or the like: ink4060ato the planned sub-pixel formation region4000a; ink4060bto the planned sub-pixel formation region4000b; and ink4060cto the planned sub-pixel formation region4000c. At the time when the inks4060a,4060band4060care applied, the vapor concentration distribution is uniform between the left-hand and right-hand sides in the X-axis direction only in the planned sub-pixel formation region4000bwhich is located at the central region of the pixel.

On the other hand, in the planned sub-pixel formation region4000a, the vapor concentration distribution is lower on the left-hand side than on the right-hand side due to the presence of the non-light-emitting cell400don the left-hand side of the region4000ain the X-axis direction. Similarly, in the planned sub-pixel formation region4000c, the vapor concentration distribution is lower on the right-hand side than on the left-hand side due to the presence of the non-light-emitting cell400eon the right-hand side of the region4000cin the X-axis direction.

In the present embodiment, the non-light-emitting cells400dand400eare present on the left-hand and right-hand sides of the planned sub-pixel formation regions4000aand4000c, respectively. In view of this, in the present embodiment, the inclination angles θ4aaand θ4dcof the respective side walls405aaand405dcof the banks405aand405dare set to be larger than the other inclination angles θ4ba, θ4bb, θ4cband θ4cc. With this structure, the pinning locations Q4aaand Q4dcof the inks4060aand4060cin the respective sidewalls405aaand405dcof the banks105aand105dbecome higher in position than the other pinning locations Q4ba, Q4bb, Q4cband Q4cc.

Note that, although not illustrated, subsequently the ink is dried, and the electron injection layer, cathode, passivation layer, etc, are layered in this order to form the display panel40.

With the above-described structure, even in the case where the non-light-emitting cells400dand400eare each provided between adjacent pixels and the inks4060a,4060band4060care applied at the same time, it is possible to restrict the film thickness of the organic light-emitting layer from becoming uneven in each of the sub-pixels400a,400band400c, and provide the display panel40having excellent light-emitting characteristics.

Note that, with regard to the structural elements that are not described in the present embodiment, corresponding structural elements of Embodiment 1 may be applied.

Firstly, in the above Embodiments 1, 2 and 3 and Modifications 1 and 2, it is schematically illustrated that the surface of each sidewall of the banks105,105a-105d,105x,105y,305a-305e, and405a-405eis planar. However, the surface of each sidewall of the banks may not necessarily be planar. For example,

FIG. 19Aillustrates a bank605whose sidewall has two surfaces: a surface

extending from a point P61to a point P62; and a surface extending from the point P62to a point P63. In this case, a pinning location Qy1during ink application is present on the surface between the points P62and P63. Here, an inclination angle θy2formed between this the surface and a virtual straight line L1passing through the point P6, is important in the relationship with the pinning location.

However, the angle θy2can be controlled by controlling an angle θy1, which is formed between the surface of the underlying layer, namely the hole injection transporting layer104, and the surface between points P61and P6, of the sidewall of the bank605, when the bank605is formed. Thus, in the actuality, the above effects can be obtained by controlling the inclination angle θy1. For example, if a bank705is formed such that an angle θy11formed between the surface of the hole injection transporting layer104and a surface between points P71and P72is larger than the angle θy1shown inFIG. 21A(seeFIG. 21B), then, as shown inFIG. 21B, an angle θy12formed between a surface between points P72and P73and a virtual straight line L2also becomes larger than the angle θy2shown inFIG. 21A.

Secondly, in the above Embodiments 1, 2 and 3 and Modifications 1 and 2, it is not specified to what part of the region of the display panel10,30or40the above-described structure can be applied. However, the above-described structure may be applied to the entire region of the display panel, or may be applied to a part of the region. As shown inFIG. 22, the display panel10can be divided formally into areas10aand10bin a direction along the surface of the display panel10, wherein the area10ais located at the center, and the area10bsurrounds the area10a. The area10ais connected to a source electrode or a drain electrode of the TFT layer below which the anodes are formed, and contributes to the emission of light. On the other hand, the area10bis not connected to any of the source electrode and drain electrode of the TFT layer below which the anodes are formed, and does not contribute to the emission of light. It is considered that, if the area10ais further divided formally into a central area10a1and a surrounding area10a2, the uneven film thickness in the organic light-emitting layers of the sub-pixels in the surrounding area10a2would be more prominent due to the state of vapor concentration distribution during the application of ink.

Note that the combined area of the surrounding area10a2and the area10bmay occupy approximately 0.5% to several percent (for example, 1%) of the total area of the panel. This range is determined by taking account of the variation in film thickness of the organic light-emitting layers when the inclination angles of the bank sidewalls are not adjusted.

In the above Embodiments 1, 2 and 3 and Modifications 1 and 2, the structures are adopted by way of example to clearly explain the structure, acts and effects of the present invention. Accordingly, the present invention is not limited to the above structures, except for such portions that are essential to the present invention. For example, the above Embodiment has adopted, as one example, a structure in which the anodes102are located below the organic light-emitting layers106in the Z axis direction, as shown inFIG. 2. However, not limited to this structure, the present invention may adopt a structure in which the cathodes108are located below the organic light-emitting layers106in the Z axis direction.

The display panel has the top-emission structure when it adopts the structure in which the cathodes108are located below the organic light-emitting layers106in the Z axis direction. In that case, the cathodes108become the reflecting electrode layers, and the electrode coating layers103are formed above the cathodes108.

Furthermore, the above Embodiments 1, 2 and 3 and Modifications do not provide a specific example of the appearance of the display device1. However, the display device1may be formed as a part of a system illustrated inFIG. 23, for example. Note that an organic EL display device does not require a backlight as a liquid crystal display device does, and thus is suitable for thin display devices and has excellent characteristics from the view point of system design.

Also, in the above Embodiments 1, 2 and 3 and Modifications 1 and 2, a so-called line bank structure is adopted for the banks105,105a-105f,105x,105y,305a-305e,405a-405e,605, and705, as shown inFIG. 3. However, not limited to this, the structure of pixel bank805shown inFIG. 24may be adopted. In this structure, a display panel80includes the pixel bank805which is composed of bank elements805aand bank elements805b, wherein the bank elements805aextend in the Y axis direction and the bank elements805bextend in the X axis direction.

As shown inFIG. 24, when the structure of pixel bank805is adopted, the same advantageous effects as the above ones can be obtained by increasing the inclination angles of the sidewalls of the bank805in the X and Y axis directions defining the sub-pixels800a,800b, and800c. More specifically, the above advantageous effects can be obtained by appropriately adjusting the inclination angles of the sidewalls indicated by the arrows B1, B2, B3, and B4.

Also, the inclination angles of the sidewalls of the banks adopted in the above Embodiments 1, 2 and 3 and Modifications 1 and 2 may be individually adjusted depending on the vapor concentration distribution observed in the ink application process and drying process when the organic light-emitting layers are formed in the manufacturing process. For example, if the drying device used in the ink drying process has a structure where the vapor flows from the outer circumference of the panel toward the center of the panel, bank sidewalls where the organic light-emitting layers are large in film thickness may have increased inclination angles. This enables the film thickness of the organic light-emitting layers to be uniform, thereby reducing the unevenness in luminance over the entire panel.

In the above Embodiments 1, 2 and 3 and in Modifications 1 and 2, the inclination angle (taper angle) of bank sidewalls is set in the same manner, without distinction between the luminescent colors (red, green, and blue). However, there may be a case where the organic light-emitting materials of the ink for the respective luminescent colors have different characteristics. In that case, the inclination angles of the bank sidewalls may be defined in accordance with the ink characteristics of each luminescent color.

The present invention is useful for providing an organic light-emitting panel and an organic display device that exhibit substantially even luminance and are capable of displaying high-quality images.

REFERENCE SIGNS LIST