OLED Emission Layer Injection Retarding for High-Brightness Efficiency
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Solution Overview
Problem
Phosphorescent OLED devices experience efficiency roll-off at high current densities due to exciton annihilation, including Triplet-Triplet Annihilation (TTA) and Exciton-Polaron quenching (TPA), leading to decreased external quantum efficiency with increasing brightness.
Innovation Solution
A light-emitting component is designed with a hole injection retarding layer and/or an electron injection retarding layer to reduce the hole and electron transport rates, respectively, thereby retarding the injection of holes and electrons into the organic light-emitting layer at high current densities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high current density is applied to phosphorescent OLED devices to increase brightness, then illumination intensity is improved, but external quantum efficiency decreases sharply due to exciton annihilation
Solution Approach 1:
The patent introduces a hole injection retarding layer as an intermediary component between the hole transport layer and the organic light-emitting layer. This intermediary layer with optimized HOMO energy level (higher than the hole transport layer by 0.19-0.29 eV) mediates the hole injection process, reducing the hole transport rate and minimizing exciton-polaron quenching at the interface, thereby maintaining high external quantum efficiency at high brightness
Solution Approach 2:
The patent applies parameter changes by optimizing the HOMO energy level of the hole injection retarding layer to be 0.19-0.29 eV higher than the hole transport layer, and controlling the hole mobility ratio between the electron blocking layer and hole injection retarding layer to be 10-100. These parameter optimizations reduce exciton concentration at interfaces and minimize exciton annihilation, maintaining efficiency at high current densities
2Illumination intensity
If high current density is applied to phosphorescent OLED devices to increase brightness, then illumination intensity is improved, but efficiency roll-off occurs due to exciton-polaron quenching
Solution Approach 1:
The hole injection retarding layer serves as a mediator that reduces direct interaction between high-density holes and excitons at the interface. By controlling hole transport rate through this intermediary layer with specific HOMO energy level (0.19-0.29 eV higher than hole transport layer), the patent minimizes exciton-polaron quenching and maintains efficiency stability at high brightness
Solution Approach 2:
The patent employs composite material strategy by combining the hole transport layer with the hole injection retarding layer having different HOMO energy levels. This composite structure with optimized energy level alignment (0.19-0.29 eV difference) creates a barrier that reduces hole injection rate and prevents exciton-polaron quenching, ensuring efficiency reliability at high current densities
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
The reduced exciton concentration at the interfaces between the transport layers and the organic light-emitting layer minimizes exciton quenching, enhancing the light-emitting efficiency and preventing efficiency roll-off at high brightness, thus improving display uniformity.
Implementation Method 1
the first functional layer group comprises a hole injection retarding layer close to the organic light-emitting layer, and the hole injection retarding layer is used for reducing a hole transport rate
Implementation Method 2
the second functional layer group comprises an electron injection retarding layer close to the organic light-emitting layer, and the electron injection retarding layer is used for reducing an electron transport rate
Implementation Method 3
Organic light-emitting Diodes (OLEDs) are widely considered to be the most promising next-generation display and illumination technology due to their unique advantages of low driving voltage, fast response, wide color gamut and self-luminescence
Data Source
AI summary
The present application provides a light-emitting component and a method for manufacturing the same, a display substrate, and a display device. The light-emitting component comprises: an anode layer stacked on one side of a base, a first functional layer group including a plurality of functional layers, an organic light-emitting layer, a second functional layer group including a plurality of functional layers, and a cathode layer; the first functional layer group comprises a hole injection delaying layer close to the organic light-emitting layer, and the hole injection delaying layer is used for reducing a hole transport rate; and/or the second functional layer group comprises an electron injection delaying layer close to the organic light-emitting layer, and the electron injection delaying layer is used for reducing an electron transport rate.