In recent years, as a display device substituted for a liquid crystal display device, an organic electroluminescence display device (hereinafter, also simply abbreviated as an “organic EL display device”) using an organic electroluminescence element (hereinafter, also simply abbreviated as an “organic EL element”) has attracted attention. The organic EL display device is a self-luminous type, has a characteristic of low power consumption, and is considered to have sufficient responsiveness even to a high-definition high-speed video signal. Development and commercialization of the organic EL display device for practical use are keenly proceeding.
In the organic EL display device, high contrast and high color reproducibility can be realized, for example, by constituting one pixel with three sub-pixels (light emitting elements) constituted by a sub-pixel having a red light emitting layer and constituted by a light emitting element that emits red light, a sub-pixel having a green light emitting layer and constituted by a light emitting element that emits green light, and a sub-pixel having a blue light emitting layer and constituted by a light emitting element that emits blue light. Meanwhile, reduction of a pixel pitch is required for high resolution. However, it becomes more difficult to constitute one pixel with such three sub-pixels as the pixel pitch becomes finer.
Therefore, development of a method for forming a white light emitting layer over all pixels and coloring white light using a color filter, that is, development of technology for constituting one pixel with three sub-pixels of a red sub-pixel (referred to as a “red light emitting element”) obtained by combining a light emitting element having a white light emitting layer (referred to as a “white light emitting element”) and a red color filter, a green sub-pixel (referred to as a “green light emitting element”) obtained by combining a white light emitting element and a green color filter, and a blue sub-pixel (referred to as a “blue light emitting element”) obtained by combining a white light emitting element and a blue color filter is proceeding. The white light emitting layer is formed as a continuous layer over the entire white light emitting element. It is unnecessary to form the red light emitting layer, the green light emitting layer, and the blue light emitting layer for each sub-pixel. Therefore, the pixel pitch can be fine. In each white light emitting element, the white light emitting layer is formed between a first electrode and a second electrode. The first electrode is formed independently in each light emitting element. Meanwhile, the second electrode is common in each light emitting element.
In such a configuration, a phenomenon that a leakage current flows between a first electrode of a certain light emitting element and a second electrode constituting a light emitting element (referred to as an “adjacent light emitting element” for convenience) adjacent to the certain light emitting element may occur. In addition, when such a phenomenon occurs, light emission occurs in a light emitting element which should not emit light originally. Meanwhile, a current in a light emitting element which should emit light is reduced. As a result, blurring occurs in an image, and the chromaticity of the entire pixels may be shifted from desired chromaticity disadvantageously.
A means for solving such a problem is known, for example, from Japanese Patent Application Laid-open No. 2014-232631. A display device disclosed in this patent publication includes, successively from a substrate side, a plurality of first electrodes each formed in each pixel, and apertures respectively opposed to the plurality of first electrodes. The display device further includes an insulation layer having covers on edge portions of the apertures, a charge injection/transport layer which is cut at the covers of the insulation layer or the resistance of which is increased and indicating at least one of a charge injection property and a charge transport property, an organic layer including one or more light emitting layers common in all the pixels, and a second electrode formed over the entire surface of the organic layer.
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