OLED Emissive Layer Composition for Narrow Spectrum and Long Lifetime
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Solution Overview
Problem
Existing organic electroluminescent devices struggle to achieve a balance of high efficiency, long lifetime, and good color purity, particularly in achieving the BT-2020 and DCPI3 color gamut, due to broad emission spectra and high costs associated with transition metal-based phosphorescence materials.
Innovation Solution
Incorporating a light-emitting layer composed of sublayers containing a host material, a phosphorescence material, a small full width at half maximum (FWHM) emitter, and optionally a thermally activated delayed fluorescence (TADF) material, which together provide narrow emission spectra and efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescence materials based on transition metals are used, then high efficiency is achieved, but cost increases and lifetime is reduced
Solution Approach 1:
The patent introduces TADF materials as intermediary components that facilitate energy transfer from phosphorescence materials to fluorescent emitters. This mediator approach allows the system to utilize the high efficiency of phosphorescence materials while transferring energy to fluorescent emitters that provide longer lifetime and narrower emission spectra, thus resolving the contradiction between efficiency and lifetime
Solution Approach 2:
The patent creates a composite light-emitting layer combining phosphorescence materials, TADF materials, and fluorescent emitters. This composite structure leverages the strengths of each component: phosphorescence materials provide high efficiency through triplet exciton utilization, TADF materials enable energy transfer, and fluorescent emitters deliver narrow emission and long lifetime, collectively resolving the efficiency-lifetime trade-off
2Use of energy by moving object
If phosphorescence materials based on transition metals are used, then high efficiency is achieved, but cost increases
Solution Approach 1:
The patent replaces expensive transition metal-based phosphorescence materials with organic fluorescent emitters that are cheaper and more abundant. Although fluorescent emitters alone have efficiency limitations, the hybrid system with TADF and phosphorescence components recovers triplet excitons through RISC, achieving high efficiency without heavy reliance on costly transition metals
Solution Approach 2:
The patent changes the material composition parameters by introducing TADF materials with specific energy level characteristics that enable efficient energy transfer. By adjusting the energy levels and concentrations of different components, the system achieves high efficiency while reducing transition metal content, thus lowering cost
3Manufacturing precision
If fluorescence or TADF emitters with narrow emission spectrum are used, then color purity is improved, but efficiency decreases and lifetime is reduced
Solution Approach 1:
The patent uses phosphorescence materials as energy pumps that transfer energy to fluorescent emitters with narrow emission spectra. The phosphorescence components act as intermediaries that capture triplet excitons and transfer energy to the fluorescent emitters, enabling the latter to emit light with high efficiency and narrow bandwidth simultaneously
Solution Approach 2:
The patent creates a composite system where phosphorescence materials and fluorescent emitters work together. The phosphorescence component handles triplet exciton management for high efficiency, while the fluorescent component provides narrow emission for color purity, achieving both properties in the composite structure
4Manufacturing precision
If fluorescence or TADF emitters with narrow emission spectrum are used, then color purity is improved, but lifetime is reduced
Solution Approach 1:
The patent introduces host-guest complex systems where the host material acts as a mediator that protects the fluorescent emitter from degradation. The host-guest complex stabilizes the fluorescent emitter while maintaining its narrow emission properties, thereby extending device lifetime without sacrificing color purity
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 results in an organic electroluminescent device with a long lifetime, high quantum yield, and narrow emission suitable for achieving the BT-2020 and DCPI3 color gamut, while reducing the reliance on expensive transition metals.
Implementation Method 1
a phosphorescence material P B and, optionally, a thermally activated delayed fluorescence (TADF) material E B may transfer energy to a small full width at half maximum (FWHM) emitter S B displaying emission of light
Implementation Method 2
consisting of one or more layers comprising a phosphorescence material
Implementation Method 3
a thermally activated delayed fluorescence (TADF) material E B
Implementation Method 4
a host material H B, a phosphorescence material P B
Data Source
AI summary
The present invention relates to a an organic electroluminescent device comprising at least one light-emitting layer B composed of one or more sublayers, wherein the one or more sublayers of the light-emitting layer B as a whole comprise at least one host material HB, at least one phosphorescence material PB, at least one small FWHM emitter SB, and optionally at least one TADF material EB, wherein SB emits light with a full width at half maximum (FWHM) of less than or equal to 0.25 eV.