CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2017-0132227, filed on Oct. 12, 2017, in the Korean Intellectual Property Office, and entitled: “Display Device,” is incorporated by reference herein in its entirety.

BACKGROUND

1. Field

Embodiments relate to a display device for improving light emission efficiency.

2. Description of the Related Art

Organic light emitting diode (“OLED”) display devices are self-light emitting display devices that display images using an OLED. The OLED display devices are currently garnering attention by virtue of their characteristics such as low power consumption, high luminance, high reaction speed, and the like.

Light emitted by the OLED is emitted not only toward the front side but also toward the lateral side of the display device. Accordingly, light emission efficiency of the display device is lowered, and power consumption of the display device may increase. Thus, there is a need for a method of improving the light emission efficiency and for reducing the power consumption in the OLED display devices.

It is to be understood that this background of the technology section is intended to provide useful background for understanding the technology and as such disclosed herein, the technology background section may include ideas, concepts or recognitions that were not part of what was known or appreciated by those skilled in the pertinent art prior to a corresponding effective filing date of subject matter disclosed herein.

SUMMARY

According to an exemplary embodiment, a display device includes: a first substrate; an organic light emitting element disposed on the first substrate and including a first electrode, an organic light emitting layer, and a second electrode; a pixel defining layer surrounding the first electrode on the first substrate; a thin film encapsulation layer on the organic light emitting element and the pixel defining layer; a high refractive index portion overlapping, on a plane, at least a portion of the first electrode on the thin film encapsulation layer; a first low refractive index portion overlapping, on a plane, the pixel defining layer on the thin film encapsulation layer and including a first inclined portion forming a first angle with the thin film encapsulation layer; a second low refractive index portion disposed, on a plane, between the first low refractive index portion and the high refractive index portion on the thin film encapsulation layer and including a second inclined portion forming a second angle with the thin film encapsulation layer; and a first reflection layer disposed, on a plane, between the first low refractive index portion and the second low refractive index portion on the thin film encapsulation layer.

The first angle may be about 45 degrees or more.

The second angle may be about 60 degrees or more.

The high refractive index portion may have a refractive index of about 1.6 or more and the first and second low refractive index portions may have refractive indices less than about 1.6.

The first low refractive index portion may have a refractive index substantially equal to a refractive index of the second low refractive index portion.

The display device may further include a circular polarization plate on the high refractive index portion and the first low refractive index portion and the second low refractive index portion.

The reflection layer may include at least one of molybdenum (Mo), an alloy (MoTi) of molybdenum and titanium, aluminum (Al), silver (Ag), APC (Ag; Pb; Cu), and platinum (Pt).

The first reflection layer may have a thickness of about 300 Å or more.

The first low refractive index portion may have a thickness less than a thickness of the second low refractive index portion.

The second low refractive index portion may be disposed on the first low refractive index portion and the first reflection layer.

According to an exemplary embodiment, a display device includes: a first substrate; an organic light emitting element disposed on the first substrate and including a first electrode, an organic light emitting layer, and a second electrode; a pixel defining layer surrounding the first electrode on the first substrate; a thin film encapsulation layer on the organic light emitting element and the pixel defining layer; a first low refractive index portion overlapping, on a plane, the pixel defining layer on the thin film encapsulation layer and including a first inclined portion forming a first angle with the thin film encapsulation layer; a second low refractive index portion including a second inclined portion forming a second angle with the thin film encapsulation layer; a third low refractive index portion spaced apart from the first low refractive index portion and overlapping, on a plane, at least a portion of the first electrode; a first reflection layer disposed between the first low refractive index portion and the second low refractive index portion on the thin film encapsulation layer; and a second reflection layer disposed between the second low refractive index portion and the third low refractive index portion on the thin film encapsulation layer. The second low refractive index portion is disposed between the first low refractive index portion and the third low refractive index portion on a plane.

The first low refractive index portion may have a refractive index substantially equal to a refractive index of the second low refractive index portion, and the second low refractive index portion may have a refractive index substantially equal to a refractive index of the third low refractive index portion.

The first reflection layer may include a material substantially equal to a material included in the second reflection layer.

The first angle and the second angle may be about 45 degrees or more.

According to an exemplary embodiment, a display device includes: a first substrate; an organic light emitting element disposed on the first substrate and including a first electrode, an organic light emitting layer, and a second electrode; a pixel defining layer surrounding the first electrode on the first substrate; a thin film encapsulation layer on the organic light emitting element and the pixel defining layer; a high refractive index portion overlapping at least a portion of the first electrode on the thin film encapsulation layer; a first low refractive index portion overlapping, on a plane, the pixel defining layer on the thin film encapsulation layer and including a first inclined portion forming a first angle with the thin film encapsulation layer; a second low refractive index portion including a second inclined portion forming a second angle with the thin film encapsulation layer; a third low refractive index portion directly contacting the high refractive index portion, spaced apart from the first low refractive index portion, and including a third inclined portion forming a third angle with the thin film encapsulation layer; a first reflection layer disposed between the first low refractive index portion and the second low refractive index portion; and a second reflection layer disposed between the second low refractive index portion and the third low refractive index portion. The second low refractive index portion is disposed between the first low refractive index portion and the third low refractive index portion on a plane.

The first low refractive index portion may have a refractive index substantially equal to a refractive index of the second low refractive index portion, and the second low refractive index portion may have a refractive index substantially equal to a refractive index of the third low refractive index portion.

The first angle and the second angle may be about 45 degrees or more.

The third angle may be about 60 degrees or more.

The high refractive index portion may have a refractive index of about 1.6 or more and the first, second and third low refractive index portions may have refractive indices less than about 1.6.

The first low refractive index portion may have a refractive index substantially equal to a refractive index of the second low refractive index portion, and the first low refractive index portion may have a refractive index substantially equal to a refractive index of the third low refractive index portion.

The foregoing is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, exemplary embodiments and features described above, further aspects, exemplary embodiments and features will become apparent by reference to the drawings and the following detailed description.

