OLED Exciton Generation Layer for Efficiency and Lifespan
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Solution Overview
Problem
Existing OLEDs face challenges in achieving high luminous efficiency and long luminous lifespan, with fluorescent materials showing low efficiency due to limited exciton use and phosphorescent materials having short lifespans due to metal complexes.
Innovation Solution
The development of an OLED structure that includes an emissive layer with an emitting material layer and a first exciton generation layer, comprising specific organic compounds that generate exciplex, adjacent to the emitting material layer, which reduces exciton concentration and prevents non-emissive quenching, thereby enhancing lifespan and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent materials comprising metal complexes are used to achieve high luminous efficiency, then luminous efficiency is improved, but luminous lifespan becomes too short for commercial use
Solution Approach 1:
The patent introduces an exciton generation layer as an intermediary between the charge generation layer and the emitting material layer. This layer comprises a first compound and a second compound that generate exciplex, serving as a mediator to reduce exciton concentration in the emitting material layer and prevent non-emissive quenching, thereby extending luminous lifespan while maintaining efficiency
Solution Approach 2:
The patent changes the chemical composition parameters of the exciton generation layer by selecting specific compounds with appropriate HOMO and LUMO energy levels. The first compound has a HOMO level higher than the second compound by 0.2-0.8 eV, and the emitting material has triplet energy level higher than the second compound, creating optimal energy level alignment to improve both efficiency and lifespan
2Duration of action of stationary object
If fluorescent materials are used to achieve long luminous lifespan, then luminous lifespan is improved, but luminous efficiency becomes low due to limited exciton use
Solution Approach 1:
The patent employs a composite material system consisting of the first compound, second compound, and emitting material with specific energy level relationships. This composite structure enables efficient exciton generation and transfer while preventing degradation, achieving both high luminous efficiency and extended lifespan by utilizing both singlet and triplet excitons without metal complexes
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 approach lowers the driving voltage and improves the luminous lifespan of OLEDs by reducing material degradation and increasing out-coupling efficiency, while also potentially reducing material costs.
Implementation Method 1
the first exciton generation layer comprise a first compound and a second compound... which reduces exciton concentration and prevents non-emissive quenching
Implementation Method 2
an organic light emitting diode that comprises a first electrode; a second electrode facing the first electrode; and an emissive layer disposed between the first electrode and the second electrode
Data Source
AI summary
An organic light emitting diode (OLED) comprises at least one exciton generation layer that can generate exciplex disposed adjacently to an emitting material layer. While emissive zone is extended to the exciton generation layer as well as the emitting material layer, exciton recombination zone is limited to the emitting material layer. The luminous lifespan of the OLED can be improved by preventing materials degradations within the emissive layer. The driving voltage of the OLED can be lowered as holes and electrons can be injected rapidly into the emitting material layer.