OLED Emission Layer with 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 excitation energy transfer components EET-1 and EET-2 with distinct chemical structures, small full width at half maximum (FWHM) emitters S B< emitting light less than 0.25 eV, and optionally host materials H B<, with specific orbital energy relationships, to optimize the light-emitting layer composition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphorescence emitters are used to achieve good efficiency and long lifetime, then the emission spectrum becomes broad (FWHM > 0.25 eV), which worsens color purity and out-coupling efficiency
Solution Approach 1:
The patent introduces an energy pump component as an intermediary that absorbs excitons and transfers energy to the fluorescent emitter. This mediator enables the system to achieve both high efficiency (through triplet exciton utilization) and narrow emission (through fluorescent emission), resolving the contradiction between lifetime and color purity
Solution Approach 2:
The light-emitting layer is designed as a composite system containing four distinct components: host material, fluorescent emitter, energy pump, and auxiliary component. This composite structure combines the advantages of different material types to achieve simultaneous improvement in efficiency, lifetime, and color purity
2Use of energy by moving object
If transition metal-based phosphorescence materials are used to achieve good efficiency, then the emission spectrum becomes broad and the cost increases due to expensive transition metals
Solution Approach 1:
The patent replaces expensive transition metal-based phosphorescence materials with organic fluorescent emitters that are cheaper and do not rely on scarce transition metals. The energy pump component enables these cheaper fluorescent materials to achieve high efficiency that previously required expensive phosphorescence materials
Solution Approach 2:
The patent substitutes the phosphorescence emission mechanism (based on triplet excitons and heavy atom effects) with a fluorescent emission mechanism driven by an energy pump. This substitution replaces the need for transition metals with pure organic materials, reducing cost while maintaining efficiency
3Manufacturing precision
If fluorescence or TADF emitters with narrow emission spectrum are used to achieve good color purity, then the efficiency decreases due to roll-off behavior and low lifetime
Solution Approach 1:
The energy pump acts as a mediator that absorbs triplet excitons (which would otherwise cause efficiency loss through non-radiative decay) and transfers energy to the fluorescent emitter. This intermediary mechanism enables the fluorescent emitter to maintain narrow emission while achieving high efficiency by utilizing both singlet and triplet excitons
Solution Approach 2:
The energy pump continuously transfers energy from triplet excitons to the fluorescent emitter, maintaining a steady supply of excitons for light emission. This continuous energy transfer process prevents the roll-off behavior typically seen in fluorescent OLEDs at high luminance, sustaining high efficiency across different operating conditions
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.
Implementation Method 1
EET-1 and/or EET-2 may transfer excitation energy to one or more small full width at half maximum (FWHM) emitters S B
Implementation Method 2
Excitons of high energy are then generated by recombination of the holes and the electrons in a light-emitting layer. The decay of such excited states (e.g., singlet states such as S1 and/or triplet states such as T1 to the ground state (S0) desirably leads to the emission of light.
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.