Light-Emitting Element Hole-Transport Layer Energy Transfer
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Solution Overview
Problem
Current light-emitting elements using phosphorescent compounds face limitations in emission efficiency, reliability, and cost, with existing structures not fully optimizing energy transfer for high efficiency and long lifetime.
Innovation Solution
A light-emitting element structure incorporating a hole-transport layer with a phosphorescent or thermally activated delayed fluorescence material, where the emission spectrum of the compound is on a shorter wavelength side than the guest material, allowing for efficient energy transfer and exclusive light emission from the guest material, enhancing emission efficiency and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a phosphorescent compound is used as the light-emitting substance, then the internal quantum efficiency can be theoretically increased to 100%, but the emission efficiency, reliability, and cost still leave room for improvement
Solution Approach 1:
The patent introduces a hole-transport layer containing a phosphorescent or TADF compound as an intermediary between the anode and the light-emitting layer. This intermediary layer facilitates efficient energy transfer to the guest material while improving element reliability. The hole-transport layer acts as a mediator that optimizes the interface between electrodes and functional layers, resolving the contradiction between high internal quantum efficiency and element reliability.
2Productivity
If the hole-transport layer contains a phosphorescent compound with emission spectrum on shorter wavelength side than guest material, then energy transfer efficiency is improved, but the device complexity increases
Solution Approach 1:
The hole-transport layer compound serves multiple functions simultaneously: it transports holes, emits phosphorescence or TADF, and transfers energy to the guest material. This multi-functionality reduces the need for separate dedicated layers, thereby improving energy transfer efficiency while minimizing the increase in device complexity.
3Use of energy by moving object
If only the guest material emits light, then the emission efficiency is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The patent designs the hole-transport layer with specific local properties: the phosphorescent or TADF compound is positioned in the hole-transport layer with its emission spectrum on the shorter wavelength side than the guest material. This localized spectral property ensures that energy transfer occurs unidirectionally to the guest material, enhancing emission efficiency while providing clear guidelines for manufacturing control.
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 structure achieves high emission efficiency and long lifetime by optimizing energy transfer, resulting in low power consumption and high reliability for light-emitting devices.
Implementation Method 1
A peak of an emission spectrum of the compound is on a shorter wavelength side than a peak of an emission spectrum of the guest material. Only the guest material emits light.
Implementation Method 2
The compound is a phosphorescent compound or a thermally activated delayed fluorescence material.
Implementation Method 3
The present invention relates to a light-emitting element, a lighting device, a light-emitting device, and an electronic device utilizing electroluminescence (EL).
Data Source
AI summary
A light-emitting element with high emission efficiency is provided. A light-emitting element with a long lifetime is provided. The light-emitting element includes an anode; a hole-transport layer over the anode, containing a hole-transport compound and a compound; a light-emitting layer over the hole-transport layer, containing a host material and a guest material; and a cathode over the light-emitting layer. The host material is an electron-transport compound. The guest material and the compound are each independently a phosphorescent compound or a thermally activated delayed fluorescence material. A peak of an emission spectrum of the compound is on a shorter wavelength side than a peak of an emission spectrum of the guest material. Only the guest material emits light.