OLED Mixed Hole Transporting Layer for Voltage and Efficiency
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Solution Overview
Problem
Current OLED apparatuses face challenges in achieving low driving voltage, improved light-emission efficiency, and extended lifespan due to limitations in the structure and properties of their hole transporting layers, which affect the balance and transfer of holes and electrons.
Innovation Solution
A method of forming an OLED apparatus with a hole transporting layer of a mixed structure, comprising two materials with different properties: one with high hole mobility and another with a higher triplet energy level, HOMO level, and thermal stability, to optimize the transfer of holes and reduce electron transfer, thereby balancing electron and hole injection and extending lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-material hole transporting layer is used, then the device structure is simple, but the driving voltage is high and light-emission efficiency is poor
Solution Approach 1:
The patent applies composite materials by forming a hole transporting layer with a mixed structure comprising two different organic materials. The first material has high hole mobility while the second material has higher triplet energy level, creating a composite structure that achieves lower driving voltage through optimized charge transport properties without significantly increasing device complexity.
Solution Approach 2:
The patent changes material parameters by selecting materials with specific properties: the first material provides high hole mobility and the second material provides higher triplet energy level. By adjusting the molecular orbital energy levels and hole mobility parameters of the constituent materials, the composite structure achieves optimized electrical characteristics and reduced driving voltage.
2Device complexity
If a single-material hole transporting layer is used, then the device structure is simple, but light-emission efficiency is poor
Solution Approach 1:
The patent uses composite materials in the hole transporting layer, combining a first material with high hole mobility and a second material with higher triplet energy level. This composite structure improves light-emission efficiency by optimizing the balance between hole and electron transport, reducing energy loss through better exciton formation in the emission layer.
Solution Approach 2:
The patent applies local quality by assigning different functional properties to different materials within the hole transporting layer. The first material primarily provides hole transport capability while the second material provides triplet energy level management, creating localized functional zones that collectively improve overall light-emission efficiency.
3Ease of manufacture
If a single-material hole transporting layer is used, then the manufacturing process is simple, but the lifespan is short
Solution Approach 1:
The patent employs composite materials to extend device lifespan by combining a first material with high hole mobility and a second material with higher thermal stability and triplet energy level. The second material's superior thermal stability protects against degradation under operating conditions, while the composite structure maintains ease of manufacture through conventional vacuum deposition processes.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating the second material with higher thermal stability into the hole transporting layer structure. This material acts as a protective component that prevents degradation of the emission layer from excessive heat and electron injection, thereby extending device lifespan before failure occurs.
4Device complexity
If a single-material hole transporting layer is used, then the material selection is simple, but electron transfer to the emission layer is excessive
Solution Approach 1:
The patent uses composite materials where the second material with higher triplet energy level serves as an energy barrier that prevents excessive electron transfer from the emission layer to the hole transporting layer. This composite structure selectively blocks harmful electron injection while maintaining hole transport functionality, reducing material selection complexity through systematic material property matching.
Data Source
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AI summary
Disclosed is an organic light emitting display (OLED) apparatus (1000) with improved efficiency and lifespan, wherein the OLED apparatus includes an anode (400), a cathode (600), and a light-emitting unit (500) disposed in-between, wherein the light-emitting unit includes a first emission layer (512), and a first hole transporting layer (511) having first and second materials, wherein the first material has a higher hole mobility than that of the second material so as to improve a transfer of holes from the first hole transporting layer (511) to the first emission layer (512), and the second material has a higher triplet energy level than that of the first material so as to reduce a transfer of electrons from the first emission layer (512) to the first hole transporting layer (511).