LED Hole Transport Layer Segmentation for Light Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing light emitting diodes (LEDs) in display devices face challenges in achieving high emission efficiency and longevity, particularly in structures where refractive index differences between layers are not optimized.
Innovation Solution
The LED structure incorporates multiple hole transport layers with distinct refractive indices, including a first, second, and third hole transport layer with specific refractive index differences, ranging from 1.30 to 2.40, to enhance light extraction and emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer hole transport structure is used, then the device complexity is low, but the light emission efficiency is insufficient
Solution Approach 1:
The hole transport region is divided into multiple hole transport layers (first, second, and third hole transport layers) with different refractive indices. This segmentation allows each layer to contribute differently to light extraction, with the high refractive index third layer positioned between the low refractive index first and second layers to create optimal optical conditions for enhanced light emission efficiency without excessive structural complexity
Solution Approach 2:
Different regions of the hole transport structure are assigned different refractive index properties. The first hole transport layer adjacent to the first electrode has a first refractive index, the second hole transport layer adjacent to the emission layer has a second refractive index, and the third hole transport layer positioned between them has a third refractive index greater than both first and second refractive indices. This local differentiation of optical properties optimizes light extraction at specific interfaces while maintaining overall structural functionality
2Productivity
If multiple hole transport layers with different refractive indices are used, then the light emission efficiency is improved, but the device complexity increases
Solution Approach 1:
The refractive index parameter is varied across different hole transport layers to optimize light emission. The first hole transport layer has a first refractive index, the second hole transport layer has a second refractive index, and the third hole transport layer has a third refractive index that is greater than both first and second refractive indices. By controlling and optimizing this optical parameter distribution, the patent achieves enhanced light extraction efficiency while managing structural complexity through systematic parameter variation rather than arbitrary design
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 multi-layered structure with varying refractive indices improves light emission efficiency by up to 19% compared to single-layer structures, enhancing the overall performance of the LED.
Implementation Method 1
a third hole transport layer disposed between the first hole transport layer and the second hole transport layer, the third hole transport layer having a third refractive index which is greater than each of the first refractive index and the second refractive index
Data Source
AI summary
A light emitting diode of an embodiment includes a first electrode, a hole transport region disposed on the first electrode, an emission layer disposed on the hole transport region, an electron transport region disposed on the emission layer, and a second electrode disposed on the electron transport region. The hole transport region includes a first hole transport layer disposed adjacent to the first electrode and having a first refractive index, a second hole transport layer disposed adjacent to the emission layer and having a second refractive index, and a third hole transport layer disposed between the first hole transport layer and the second hole transport layer and having a third refractive index which is greater than each of the first refractive index and the second refractive index, thereby showing high light extraction efficiency and high emission efficiency properties.