OLED Emission Layer with TADF Energy Transfer for Narrow Color Gamut
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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 the use of expensive transition metal-based phosphorescence materials.
Innovation Solution
Incorporating a light-emitting layer composed of excitation energy transfer components EET-1 and EET-2, small full width at half maximum (FWHM) emitters S B< , and optionally host materials H B< , where EET-1 and EET-2 are structurally distinct TADF materials with specific energy level differences, to facilitate efficient excitation energy transfer and narrow emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescence emitters are used to achieve high efficiency, then efficiency is improved, but emission spectrum becomes broad leading to poor color purity
Solution Approach 1:
The light-emitting layer is segmented into multiple functional sublayers: a first sublayer containing phosphorescence emitter EET-1 for efficient energy conversion, a second sublayer containing TADF emitter EET-2 for spectral narrowing, and a third sublayer containing fluorescent emitter S for color purity. This segmentation allows each material to perform its optimal function while collectively achieving both high efficiency and narrow emission spectrum.
2Use of energy by moving object
If transition metal based phosphorescence materials are used, then efficiency is improved, but cost increases due to expensive materials
Solution Approach 1:
The patent introduces TADF emitter EET-2 as an intermediary between the phosphorescence emitter EET-1 and the final fluorescent emitter S. The TADF emitter receives energy from the phosphorescence emitter and transfers it to the fluorescent emitter, enabling the system to achieve high efficiency while reducing dependence on expensive transition metal materials, thus lowering overall device cost.
3Manufacturing precision
If narrow emission spectrum emitters are used to achieve good color purity, then color purity is improved, but efficiency decreases due to roll-off behavior
Solution Approach 1:
The patent merges three different emission mechanisms (phosphorescence, TADF, and fluorescence) into a single integrated light-emitting layer. The phosphorescence emitter EET-1 provides high efficiency with long lifetime, the TADF emitter EET-2 enables narrow emission spectrum for color purity, and the fluorescent emitter S delivers the final narrow emission. This combination allows the device to achieve both high efficiency and good color purity simultaneously.
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 solution results in an organic electroluminescent device with a long lifetime, high quantum yield, and narrow emission, effectively achieving the BT-2020 and DCPI3 color gamut while reducing the need for costly transition metals.
Implementation Method 1
one or more excitation energy transfer components EET-1, one or more excitation energy transfer components EET-2, one or more small full width at half maximum (FWHM) emitters S
Implementation Method 2
both EET-1 and EET-2 are TADF materials
Implementation Method 3
organic electroluminescent device comprising one or more light-emitting layers B
Data Source
AI summary
The present invention relates to organic electroluminescent devices comprising one or more light-emitting layers B, each of which is composed of one or more sublayers comprising as a whole one or more excitation energy transfer components EET-1, one or more excitation energy transfer components EET-2, one or more small full width at half maximum (FWHM) emitters SB emitting light with an FWHM of less than or equal to 0.25 eV. Furthermore, the present invention relates to a method for generating light by means of an organic electroluminescent device according to the present invention.