Host Material Combination for OLED Charge Balance
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in achieving high luminous efficiency, power efficiency, and long lifetime, particularly due to imbalances in charge injection and transport within the light-emitting layer.
Innovation Solution
The use of a specific combination of host materials, comprising a first host material represented by a particular compound formula and a second host material represented by another compound formula, which together enhance the charge balance and efficiency of the light-emitting layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single host material with strong hole injection and transport characteristic is used, then hole transport efficiency is improved, but electron injection and transport becomes insufficient causing charge imbalance
Solution Approach 1:
The host material is segmented into two distinct components: a first host material (formula 1) providing strong hole injection and transport, and a second host material (formula 2) providing electron injection and transport. This segmentation allows each component to specialize in one charge type, resolving the charge balance issue while maintaining high productivity.
Solution Approach 2:
The patent uses a composite host material system combining two different organic compounds with complementary charge transport properties. The first host material (formula 1) and second host material (formula 2) work synergistically to provide both hole and electron transport capabilities, achieving balanced charges and high efficiency simultaneously.
2Illumination intensity
If higher luminance is achieved in OLED, then display brightness is improved, but lifetime decreases due to efficiency degradation
Solution Approach 1:
The patent changes the chemical parameters of the host materials by introducing specific molecular structures (formula 1 and formula 2) with optimized electronic properties. This parameter optimization enables the device to maintain high efficiency at high luminance, thereby extending lifetime while preserving brightness.
Solution Approach 2:
By using composite host materials with complementary properties, the system achieves stable charge balance across different luminance levels. This prevents efficiency degradation even at high brightness, allowing the OLED to maintain both high luminance and extended operational lifetime.
3Use of energy by moving object
If phosphorescent materials are used to improve luminous efficiency, then light output is enhanced, but device lifetime becomes insufficient for practical applications
Solution Approach 1:
The patent optimizes the molecular parameters of the host materials (formulas 1 and 2) to achieve better charge balance and reduced degradation mechanisms. This parameter optimization allows the device to maintain high luminous efficiency while significantly extending lifetime for practical applications in TVs and lighting.
Data Source
AI summary
The present disclosure relates to a plurality of host materials comprising a first host material comprising a compound represented by formula 1, and a second host material comprising a compound represented by formula 2, and an organic electroluminescent device comprising the same. By comprising a specific combination of compounds as host materials, it is possible to provide an organic electroluminescent device having higher luminous efficiency, higher power efficiency, and/or better lifetime properties, compared to conventional organic electroluminescent devices.