Composite OLED Anode Structure for Brightness and Hole Injection
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Solution Overview
Problem
In OLED and Micro OLED displays, the brightness is limited by the anode electrode's work function and reflectivity, which affects hole injection and light emission, as a lower work function and high reflectivity hinder the efficient operation of the organic light-emitting device.
Innovation Solution
The display panel design includes an anode electrode with a first transparent conductive layer and a metal layer stacked such that the transparent conductive layer covers the metal layer, with a higher work function than the metal layer and higher reflectivity, enhancing hole injection and light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a metal layer with high reflectivity is used in the anode electrode, then light extraction efficiency is improved, but work function is too low which hinders hole injection
Solution Approach 1:
The anode electrode is segmented into two distinct functional layers: a metal layer (Al, Ag, or Mo) providing high reflectivity for light extraction, and a transparent conductive layer (ITO, IZO, or AZO) providing high work function for efficient hole injection. Each layer performs its specialized function without compromise.
Solution Approach 2:
The anode electrode uses a composite structure combining metal material and transparent conductive material. The metal layer contributes high reflectivity (≥80%) while the transparent conductive layer contributes high work function (≥4.60 eV), creating a composite electrode that achieves both properties simultaneously.
2Reliability
If a transparent conductive layer with high work function is used to improve hole injection, then hole injection efficiency is improved, but reflectivity decreases which reduces light extraction
Solution Approach 1:
The anode electrode is segmented into two distinct functional layers: a metal layer (Al, Ag, or Mo) providing high reflectivity for light extraction, and a transparent conductive layer (ITO, IZO, or AZO) providing high work function for efficient hole injection. Each layer performs its specialized function without compromise.
Solution Approach 2:
The anode electrode uses a composite structure combining metal material and transparent conductive material. The metal layer contributes high reflectivity (≥80%) while the transparent conductive layer contributes high work function (≥4.60 eV), creating a composite electrode that achieves both properties simultaneously.
3Illumination intensity
If the first transparent conductive layer completely covers the metal layer, then light extraction is enhanced, but manufacturing precision requirements increase
Solution Approach 1:
The first transparent conductive layer is designed to completely cover the metal layer with an orthographic projection that extends beyond the metal layer boundaries. This excessive coverage ensures full optical functionality while providing manufacturing tolerance for uniform deposition processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the brightness of the display panel by increasing hole injection into the light-emitting layer and enhancing light extraction efficiency, resulting in higher luminous brightness.
Implementation Method 1
the reflectivity of the anode electrode affects the amount of the light finally emitted from the organic light-emitting device
Implementation Method 2
A lower work function of the anode electrode is not conducive to the injection of holes from the anode electrode
Data Source
AI summary
A display panel and a manufacturing method thereof, and a display apparatus are provided. The display panel includes: a base substrate, a plurality of pixels, and a drive circuit. At least one of the pixels includes a light-emitting device; the light-emitting device includes an anode electrode and a light-emitting layer; the anode electrode includes a first transparent conductive layer and a metal layer, the first transparent conductive layer completely covers the metal layer, and an orthographic projection of the metal layer on the base substrate is located in an orthographic projection of the first transparent conductive layer on the base substrate; the light-emitting layer is stacked with the anode electrode and is located on a side of the first transparent conductive layer facing away from the metal layer; the drive circuit is located between the base substrate and the anode electrode.