TECHNICAL FIELD

The present disclosure relates to a light emitting element and a display device.

BACKGROUND ART

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.

CITATION LIST

Patent Document

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-232631

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

As described above, in the display device disclosed in the above patent publication, the charge injection/transport layer is cut at covers of the insulation layer or the resistance thereof is increased, and therefore a phenomenon that a leakage current flows between a first electrode of a certain light emitting element and a second electrode constituting an adjacent light emitting element hardly occurs. However, in some cases, even in such a configuration, prevention of generation of a leakage current may be insufficient.

Therefore, an object of the present disclosure is to provide a light emitting element having a configuration and a structure in which a phenomenon that a leakage current flows between a first electrode in a certain light emitting element and a second electrode constituting an adjacent light emitting element hardly occurs, and a display device constituted by the light emitting element.

Solutions to Problems

The light emitting element of the present disclosure for achieving the above object includes:

a first electrode formed on a base body;

a first insulation layer formed on the base body and the first electrode and having an aperture portion in which a part of the first electrode is exposed;

a second insulation layer formed on the first insulation layer and having a protruding end portion protruding from the aperture portion disposed in the first insulation layer;

a third insulation layer formed on the second insulation layer and having an end portion recessed from the protruding end portion of the second insulation layer;

a charge injection/transport layer formed over the second insulation layer and the third insulation layer from the first electrode;

an organic layer formed on the charge injection/transport layer and including a light emitting layer formed of an organic light emitting material; and

a second electrode formed on the organic layer, and

at least a part of the charge injection/transport layer is discontinuous at the protruding end portion of the second insulation layer.

In order to achieve the above object, the display device of the present disclosure is formed of a plurality of the above light emitting elements of the present disclosure arranged in a two-dimensional matrix.

Effects of the Invention

In the light emitting element of the present disclosure or a light emitting element constituting the display device of the present disclosure (hereinafter, these light emitting elements are collectively referred to as a “light emitting element or the like of the present disclosure” for convenience), the protruding end portion protruding from the aperture portion (that is, the protruding end portion protruding from the first insulation layer and the third insulation layer) is disposed in the second insulation layer sandwiched by the first insulation layer and the third insulation layer. Therefore, at least a part of the charge injection/transport layer formed over the second insulation layer and the third insulation layer from the first electrode is reliably discontinuous at the protruding end portion. That is, the charge injection/transport layer is reliably cut at the protruding end portion of the second insulation layer or the resistance thereof is increased, and therefore occurrence of a phenomenon that a leakage current flows between a first electrode of a certain light emitting element and a second electrode constituting an adjacent light emitting element can be reliably prevented. Note that effects described herein are merely illustrative, and are not restrictive. In addition, an additional effect may be present.

