OLED Hole Transport Layer Dual Sublayer Structure
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Solution Overview
Problem
Existing OLEDs face challenges in achieving efficient light emission and long lifespan while operating at low driving voltage, primarily due to limitations in the design of the hole injection layer.
Innovation Solution
The proposed organic light emitting device incorporates a first hole transport layer with a dual sublayer structure, where the first hole sublayer is located between the second hole sublayer and the anode, and the materials in these sublayers are specifically chosen to optimize hole transport and injection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional single-layer hole transport layer is used, then the device structure is simple, but the hole transport efficiency and energy level alignment are insufficient
Solution Approach 1:
The hole transport layer is divided into multiple sublayers (first hole transport sublayer, second hole transport sublayer, third hole transport sublayer) with different materials and functions. Each sublayer is optimized for specific hole transport tasks, improving overall hole injection efficiency and energy level alignment while maintaining manageable structural complexity
Solution Approach 2:
The patent employs composite material design in the hole transport layer, using different organic compounds (such as TAPC, TCTA, TAPB) with complementary properties in each sublayer. This composite approach enables synergistic effects that enhance hole transport efficiency and energy level matching beyond what single materials can achieve
2Reliability
If the hole injection layer design is optimized for high efficiency, then light emitting efficiency improves, but operating voltage increases
Solution Approach 1:
Different sublayers of the hole transport layer are designed with locally optimized properties: the first sublayer near the anode focuses on hole injection with appropriate HOMO level alignment, while subsequent sublayers optimize for hole transport with higher mobility materials. This local optimization allows efficient hole injection at low voltage without compromising overall device performance
Solution Approach 2:
The patent systematically adjusts key parameters including HOMO energy levels, hole mobility, and layer thickness across different sublayers. By optimizing these parameters in each sublayer, the device achieves high light emitting efficiency at reduced operating voltages through improved charge injection and transport
3Reliability
If materials with high hole mobility are used in the hole transport layer, then hole transport efficiency improves, but color crosstalk increases
Solution Approach 1:
The hole transport layer is segmented into multiple sublayers with progressively optimized hole mobility. This segmentation allows control over hole distribution, ensuring efficient transport while preventing excessive hole accumulation that could cause color crosstalk between adjacent pixels
Solution Approach 2:
The multi-sublayer structure acts as an intermediary system that mediates between high hole mobility requirements and color crosstalk prevention. Each sublayer serves as a transition zone that gradually adjusts hole transport properties, enabling efficient transport while maintaining color purity through controlled charge distribution
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 mobility of holes and improves the energy level alignment, resulting in improved light emitting efficiency, reduced color crosstalk, and extended device lifespan at low operating voltages.
Implementation Method 1
a first hole transport layer and a first light emitting layer which are arranged between the anode and the cathode, wherein the first hole transport layer is located between the first light emitting layer and the anode
Implementation Method 2
A light emitting principle of the OLED is to inject holes and electrons into the light emitting layer from the anode and the cathode respectively. When the electrons and the holes meet in the light emitting layer, the electrons and the holes recombine to produce excitons. When transforming from an excited state to a ground state, these excitons emit light.
Data Source
AI summary
An organic light emitting device includes an anode, a cathode, and a first hole transport layer and a first light emitting layer arranged between the anode and the cathode, wherein the first hole transport layer is located between the first light emitting layer and the anode; the first hole transport layer at least includes a first hole sublayer and a second hole sublayer; a material of the first hole sublayer includes a first material and a second material, and a material of the second hole sublayer includes at least one of the first material and the second material.