OLED Hole Transport Layer Structure for Balanced Charge Recombination
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Solution Overview
Problem
Existing organic light emitting devices face challenges in optimizing the hole transport layers to enhance efficiency and performance, particularly in the recombination of holes and electrons for improved light emission.
Innovation Solution
Incorporating specific hole transport materials represented by Formulas 1 to 4, along with a thermally activated delayed fluorescence emission material in the emission layer, to optimize the hole transport region and enhance the recombination of holes and electrons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional hole transport materials are used, then device structure is simple, but emission efficiency is low and device life is short
Solution Approach 1:
The hole transport region is divided into multiple layers (hole injection layer, first hole transport layer, second hole transport layer) with different materials and functions. Each layer is optimized for specific charge transport requirements, resulting in improved emission efficiency and device life through balanced charge transport.
Solution Approach 2:
The patent employs composite material structures in the hole transport region, combining materials with different properties (e.g., high hole mobility materials, materials with specific LUMO levels) to achieve optimal charge transport and balance between holes and electrons, thereby improving emission efficiency.
2Reliability
If inadequate material selection is used in hole transport region, then manufacturing is easier, but charge transport balance is poor
Solution Approach 1:
The patent optimizes key parameters of hole transport materials including HOMO levels (5.5-6.5 eV), LUMO levels (2.0-3.5 eV), and hole mobility (10^-6 to 10^-3 cm²/Vs). These parameter specifications ensure proper charge transport balance while maintaining compatibility with standard manufacturing processes.
Solution Approach 2:
The hole transport layers act as intermediaries between the anode and the emission layer, facilitating balanced charge transport. The materials are selected to mediate between the high work function anode and the emission layer, ensuring proper hole injection and transport without requiring complex manufacturing 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
The proposed configuration improves the efficiency and performance of organic light emitting devices by optimizing the hole transport layers, leading to enhanced light emission and device performance.
Implementation Method 1
holes and electrons injected from an anode and a cathode recombine in an emission layer, and a luminescent material including an organic compound in the emission layer emits light
Implementation Method 2
The emission layer may include an emission material containing a donor and an acceptor, the emission material being a thermally activated delayed fluorescence material
Data Source
AI summary
An organic light emitting device including an anode; a hole transport region on the anode; an emission layer on the hole transport region; an electron transport region on the emission layer; and a cathode on the electron transport region, wherein the hole transport region includes: a first hole transport layer including a first hole transport material represented by the following Formula 1 or a second hole transport material represented by the following Formula 2; and a second hole transport layer on the first hole transport layer, the second hole transport layer including a third hole transport material represented by the following Formula 3 or a fourth hole transport material represented by the following Formula 4: