Quantum Dot Light-Emitting Element Hole Transport Layer Composition
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Solution Overview
Problem
Current light-emitting devices with quantum dots require enhanced efficiency of light emission, which can be achieved by improving the configuration of the hole transport layer.
Innovation Solution
A light-emitting element with a hole transport layer having a first region adjacent to the anode and a second region closer to the light-emitting layer, where the ratio of O to Ni in the first region is higher than in the second region, facilitating efficient hole transport and carrier balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hole transport layer uses a uniform composition, then the device structure is simple, but the hole transport efficiency to the light-emitting layer is insufficient
Solution Approach 1:
The hole transport layer is designed with spatially varying composition: the first region (adjacent to anode) has higher Ni content while the second region (adjacent to light-emitting layer) has higher Mg content. This local quality variation optimizes hole transport efficiency at different positions within the layer, resolving the contradiction between transport efficiency and structural simplicity.
Solution Approach 2:
The hole transport layer is segmented into two distinct regions with different compositions. The first region contains metal oxide with higher Ni content for initial hole transport, while the second region contains metal oxide with higher Mg content for efficient interface contact with the light-emitting layer. This segmentation allows each region to perform its specific function optimally.
2Productivity
If the hole transport layer is optimized for maximum hole transport, then light emission efficiency improves, but carrier balance in the light-emitting layer may be disrupted
Solution Approach 1:
The composition parameters of the hole transport layer are precisely controlled: the first region has Ni content of 40-80 atom% while the second region has Ni content of 10-40 atom%. This parameter variation ensures efficient hole transport while maintaining proper carrier balance in the light-emitting layer, as the gradual composition transition prevents excessive hole accumulation.
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 enhances the efficiency of light emission while maintaining the reliability of the light-emitting device by improving hole transport and carrier balance in the light-emitting layer.
Implementation Method 1
a hole transport layer disposed between the anode and light-emitting layer... improves the efficiency of hole transport from its hole transport layer to its light-emitting layer
Data Source
AI summary
A light-emitting element has the following: a cathode; an anode; a light-emitting layer disposed between the cathode and the anode, and containing quantum dots; and a hole transport layer disposed between the anode and light-emitting layer. The hole transport layer has a first region adjacent to the anode. The hole transport layer also has a second region closer to the light-emitting layer than the first region is. The second region adjoins to the light-emitting layer. The first region has an ionization potential larger than an ionization potential of the second region and larger than an ionization potential of the light-emitting layer.