US-12622104-B2 - Semiconductor light emitting device for a display panel and display device including same

US12622104B2US 12622104 B2US12622104 B2US 12622104B2US-12622104-B2

Abstract

The embodiment relates to a semiconductor light emitting device for a display panel and a display device including the same. The semiconductor light emitting device can include a light emitting structure comprising a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer, a first electrode layer electrically connected to the first conductivity type semiconductor layer, a second reflective electrode layer electrically connected to the second conductivity-type semiconductor layer, a passivation layer disposed on the light emitting structure, a first reflective electrode layer disposed on a side surface of the light emitting structure. The first reflective electrode layer can include a first-first reflective electrode layer in contact with a side surface of the light emitting structure and a first-second reflective electrode layer connected to the first-first reflective electrode layer and disposed on the passivation layer.

Inventors

Hyungseok Bang
Sukkoo JUNG
Hwankuk YUH
Jaechoon LEE

Assignees

LG ELECTRONICS INC.

Dates

Publication Date: 20260505
Application Date: 20220906
Priority Date: 20210906

Claims (7)

1 . A display device comprising: a first electrode and a second electrode spaced apart from each other on a predetermined substrate; an insulating layer disposed on the first and second electrodes; a first barrier wall disposed on the insulating layer and comprising a first assembly hole; a semiconductor light emitting device disposed in the first assembly hole, the semiconductor light emitting device comprising a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode layer electrically connected to the first conductivity type semiconductor layer; a passivation layer disposed on the light emitting structure; a first reflective electrode layer disposed on a side surface of the light emitting structure; a third reflective layer in the insulating layer; and a second scattering structure layer on a bottom surface of the light emitting structure of the semiconductor light emitting device.
2 . The display device according to claim 1 , wherein the first reflective electrode layer comprising a first-first reflective electrode layer in contact with the side surface of the light emitting structure and a first-second reflective electrode layer connected to the first-first reflective electrode layer and disposed on the passivation layer.
3 . The display device according to claim 2 , further comprising a second passivation layer disposed on the first-second reflective electrode layer.
4 . A display device comprising: a first electrode and a second electrode spaced apart from each other on a predetermined substrate; an insulating layer disposed on the first and second electrodes; a first barrier wall disposed on the insulating layer and comprising a first assembly hole; a semiconductor light emitting device disposed in the first assembly hole, the semiconductor light emitting device comprising a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode layer electrically connected to the first conductivity type semiconductor layer; a passivation layer disposed on the light emitting structure; a first reflective electrode layer disposed on a side surface of the light emitting structure; a first scattering structure layer disposed on a bottom surface of the light emitting structure; and a first light absorbing layer disposed under the insulating layer, wherein the first reflective electrode layer comprises a first-first reflective electrode layer in contact with a side surface of the light emitting structure, and a first-second reflective electrode layer connected to the first-first reflective electrode layer and disposed on the passivation layer.
5 . The display device according to claim 4 , further comprising a second insulating layer disposed on the first barrier wall and a second light absorbing layer disposed on the second insulating layer.
6 . A display device comprising: a first electrode and a second electrode spaced apart from each other on a predetermined substrate; an insulating layer disposed on the first and second electrodes; a first barrier wall disposed on the insulating layer and comprising a first assembly hole; a semiconductor light emitting device disposed in the first assembly hole, the semiconductor light emitting device comprising a light emitting structure including a first conductivity type semiconductor layer, an active layer, and a second conductivity type semiconductor layer; a first electrode layer electrically connected to the first conductivity type semiconductor layer; a passivation layer disposed on the light emitting structure; a first reflective electrode layer disposed on a side surface of the light emitting structure; and a first light absorbing layer disposed under the insulating layer.
7 . The display device according to claim 6 , further comprising a second insulating layer disposed on the first barrier wall and a second light absorbing layer disposed on the second insulating layer.

Description

CROSS-REFERENCE TO RELATED APPLICATION Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of an earlier filing date of and the right of priority to PCT Application No. PCT/KR2021/012009, filed on Sep. 6, 2021, the contents of which are incorporated by reference herein in its entirety. BACKGROUND OF THE DISCLOSURE 1. Field of the Disclosure The embodiment relates to a semiconductor light emitting device for a display panel, and a display device including the same. 2. Background of the Related Art Large-area displays include liquid crystal displays (LCD), OLED displays, and micro-LED displays. A micro-LED display is a display using a micro-LED, which is a semiconductor light emitting device having a diameter or cross-sectional area of 100 μm or less, as a display device. Micro-LED display uses micro-LED, which is a semiconductor light emitting device, as a display device. Therefore, Micro-LED display uses micro-LED has excellent performance in many characteristics such as contrast ratio, response speed, color gamut, viewing angle, brightness, resolution, lifespan, luminous efficiency and luminance. In particular, micro-LED displays have the advantage of being able to separate and combine screens in a modular way, so that size or resolution can be freely adjusted and flexible displays can be implemented. However, since large-sized micro-LED displays require millions of micro-LEDs, there is a technical problem in that it is difficult to quickly and accurately transfer micro-LEDs to a display panel. Transfer technologies that have been recently developed include a pick and place process, a laser lift-off method, or a self-assembly method. Among these, the self-assembly method is a method in which the semiconductor light emitting device finds an assembly position in a fluid and is advantageous for realization of a large-screen display device. Recently, although a micro-LED structure suitable for self-assembly has been proposed in U.S. Pat. No. 9,825,202, etc., research on a technology for manufacturing a display through self-assembly of micro-LED is still insufficient. In particular, in the case of rapidly transferring millions of semiconductor light emitting devices to a large display in the prior art, although the transfer speed can be improved, there is a technical problem in that the transfer error rate can be increased, so that the transfer yield is lowered. In the related art, a self-assembly method using dielectrophoresis (DEP) has been attempted, but the self-assembly rate is low due to the non-uniformity of the DEP force. Meanwhile, in order for the semiconductor light emitting device to function as a light emitting source of a display panel rather than a light emitting source of lighting, it is very important to secure a color viewing angle, and high light efficiency is also required to reduce power consumption. However, in order to secure a color viewing angle, the ratio of R, G, and B color light intensity to the emission angle in the required range is required to be equal, and the R, G, B color combination must maintain the same color coordinates. Accordingly, it is very important to match the light quantity ratio according to the light output angle of the R, G, and B light sources in order to secure a color viewing angle and high light output efficiency for a semiconductor light emitting device functioning as a display element of a display panel. In particular, according to internal research, in a semiconductor light emitting device that functions as a display device of a display panel, a side lobe phenomenon occurs in which the luminance is increased by emitting in the direction of the pixel on the side rather than the direction on the top side where the viewer is located in the luminance profile. FIGS. 1A to 1C are luminance profile data of a Micro-LED-based display in the related art. Specifically, FIG. 1A is a data of the output characteristic of the side emission light (Ls) dominant in the micro-LED display of the related art, FIG. 1B is a luminance profile of the panel by the side emission light (Ls), and FIG. 1C is a luminance profile distribution diagram for each angle of a Micro-LED-based display. Referring to FIG. 1A, since the area of the side surface of the micro-LED chip is relatively large compared to the top surface, the ratio of the side emission light (Ls) emitted to the side surface of the micro-LED chip is high. Specifically, as shown in FIG. 1B, the side emission light (Ls) to the side of the micro-LED chip proceeds at a large angle. Accordingly, a) the ratio of the light above a total reflection angle may increase, thereby reducing the light efficiency, and 2) a side lobe of the luminance profile by the light emitted at a large angle happens, especially as shown in FIG. 1C, 3) Each RGB chip has a different refractive index and geometric shape. Therefore, it causes difficulty in matching the ratio of the light of the three-color wavelengths from all angles. Accor