This application claims the priority benefit of Korean Patent Application No. 10-2018-0173032, filed on Dec. 28, 2018, which is hereby incorporated by reference as if fully set forth herein.

BACKGROUND

Technical Field

The present disclosure relates to a display device, and more particularly, to a display device having a reflective electrode for improving light-extraction efficiency.

Discussion of the Related Art

Generally, an electronic appliance, such as a monitor, a television (TV), a laptop computer, or a digital camera, includes a display device to display an image. In an example, the display device may include a plurality of light-emitting elements. Each of the light-emitting elements may emit light displaying a specific color. Furthermore, each of the light-emitting elements may include a light-emitting layer between a lower electrode and an upper electrode.

The display device may use a reflective electrode for improving efficiency of the light-emitting element. For example, in the display device, the reflective electrode may include a flat region and an inclined region. The light-emitting element may be disposed on the flat region of the reflective electrode. Thus, in the display device, the light confined by the total reflection may be emitted to the outside by the inclined region of the reflective electrode.

However, because the light emitted from the inclined region of the reflective electrode has brightness and color coordinates that may be different from the light reflected by the flat region of the reflective electrode, brightness and color of the image realized by the display device may be degraded due to the light emitted from the inclined region of the reflective electrode.

SUMMARY

Accordingly, the present disclosure is directed to a display device having a reflective electrode that substantially obviates one or more problems due to limitations and disadvantages of the related art.

An aspect of the present disclosure is to provide a display device that may be capable of improving light-extraction efficiency without quality deterioration of the realized image.

Another aspect of the present disclosure is to provide a display device where the light emitted from the inclined region of the reflective electrode may have brightness and color coordinates that are the same as those of the light reflected by the flat region of the reflective electrode.

Additional advantages, objects, and features of the disclosure will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the disclosure. The objectives and other advantages of the disclosure may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with the purpose of the disclosure, as embodied and broadly described herein, a display device comprises a reflective electrode including a first region and a second region inclined relative to the first region; a lower electrode on the first region of the reflective electrode; a bank insulating layer covering an edge of the lower electrode, the bank insulating layer extending onto the second region of the reflective electrode; an upper electrode on a portion of the lower electrode exposed by the bank insulating layer, the upper electrode extending onto the bank insulating layer; and a light-emitting layer between the lower electrode and the upper electrode, the light-emitting layer extending between the bank insulating layer and the upper electrode. An optical path between the second region of the reflective electrode and the upper electrode is the same as an optical path between the first region of the reflective electrode and the upper electrode.

A spacing distance between the second region of the reflective electrode and the upper electrode may be different from a spacing distance between the first region of the reflective electrode and the upper electrode.

The light-emitting layer may be in contact with the lower electrode and the bank insulating layer.

The refractive index of the bank insulating layer may be smaller than the refractive index of the lower electrode, and a thickness of the bank insulating layer on the second region of the reflective electrode may be greater than a thickness of the lower electrode on the second region of the reflective electrode.

A resonance layer may be between the first region of the reflective electrode and the lower electrode, wherein the resonance layer may extend between the second region of the reflective electrode and the bank insulating layer.

A thickness of the resonance layer between the first region of the reflective electrode and the lower electrode may be the same as a thickness of the resonance layer between the second region of the reflective electrode and the bank insulating layer.

The resonance layer may include at least one contact hole partially exposing the first region of the reflective electrode, and the contact hole of the resonance layer may overlap with the bank insulating layer.

The bank insulating layer may include an inorganic insulating material.

In another aspect, a display device comprises a lower electrode on a lower substrate; a first bank insulating layer spaced from the lower electrode, the first bank insulating layer having an inclined side surface that faces the lower electrode; a second bank insulating layer covering an edge of the lower electrode and on the inclined side surface of the first bank insulating layer; a reflective electrode between the lower substrate and the lower electrode, the reflective electrode extending between the first bank insulating layer and the second bank insulating layer; a light-emitting layer on a portion of the lower electrode exposed by the second bank insulating layer; and an upper electrode on the light-emitting layer, wherein a thickness ratio of the second bank insulating layer and the lower electrode is the same as the refractive index ratio of the lower electrode and the second bank insulating layer.

The second bank insulating layer and the lower electrode may be in contact with the reflective electrode.

The second bank insulating layer may include a material different from the first bank insulating layer.

The first bank insulating layer may include an organic insulating material.

The inclined side surface of the first bank insulating layer may include a first region having a first inclination angle, and a second region having a second inclination angle that is smaller than the first inclination angle, and the first region of the first bank insulating layer may be between the lower substrate and the second region of the first bank insulating layer.

The first region of the first bank insulating layer may have a vertical distance larger than a thickness of the reflective electrode.

An over-coat layer may be between the lower substrate and the lower electrode, wherein the second bank insulating layer may include a same material as the over-coat layer.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the disclosure as claimed.

