Nitrogen Heterocyclic TADF Compounds for OLED Efficiency
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Solution Overview
Problem
Current organic electroluminescent materials, particularly phosphorescent materials, face challenges with efficiency and lifespan, especially for blue phosphorescence, and there is a need for novel thermally activated delayed fluorescence (TADF) materials with enhanced performance to match the efficiency of phosphorescent materials without using rare metal elements.
Innovation Solution
Development of nitrogen-containing heterocyclic compounds with specific molecular structures that facilitate thermally activated delayed fluorescence, including compounds with general formulas (I), (II), and (III), which are used in organic photoelectric apparatuses as light-emitting layers, hole-transport layers, or doping materials to enhance light-emitting efficiency and reduce material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If phosphorescent materials are used in the light-emitting layer of OLED, then the quantum efficiency can reach 100% by utilizing both singlet and triplet excitons, but the material cost is relatively high due to the use of rare metal elements and the lifespan is reduced especially for blue phosphorescence
Solution Approach 1:
The patent replaces expensive phosphorescent materials containing rare metal elements with organic fluorescent materials that can achieve comparable efficiency through TADF mechanisms, eliminating the need for costly and unstable rare metal complexes while maintaining high quantum efficiency
Solution Approach 2:
The patent modifies the energy level parameters of the organic compounds by designing specific molecular structures with appropriate HOMO-LUMO gaps and energy level alignments, enabling efficient reverse intersystem crossing and achieving high quantum efficiency without rare metals
2Use of energy by moving object
If phosphorescent materials are used in the light-emitting layer of OLED, then the quantum efficiency can reach 100% by utilizing both singlet and triplet excitons, but the material cost is relatively high due to the use of rare metal elements
Solution Approach 1:
The patent substitutes expensive phosphorescent materials with rare metal elements with inexpensive organic fluorescent materials that utilize TADF mechanisms, achieving comparable quantum efficiency while dramatically reducing material costs by eliminating rare metal dependencies
Solution Approach 2:
The patent replicates the high efficiency function of phosphorescent materials using organic compounds with TADF characteristics, copying the desired performance (high quantum efficiency) through a different, more cost-effective material system
3Use of energy by moving object
If blue phosphorescence materials are applied in the OLED, then the light-emitting efficiency can be improved, but the lifespan is reduced
Solution Approach 1:
The patent replaces unstable blue phosphorescent materials with stable organic fluorescent materials exhibiting TADF, achieving comparable light-emitting efficiency while significantly improving device lifespan by eliminating the inherent instability of blue phosphorescent complexes
Solution Approach 2:
The patent converts the traditionally harmful non-radiative decay of triplet excitons into a beneficial mechanism by designing TADF materials where triplet excitons can undergo reverse intersystem crossing to emit photons, transforming what was previously a loss channel into a productive light-emitting pathway
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 nitrogen-containing heterocyclic compounds achieve a significant thermally activated delayed fluorescence effect, leading to improved light-emitting efficiency comparable to phosphorescent materials, with reduced material costs and extended lifespan, while being applicable in various organic photoelectric devices such as OLEDs, solar cells, and sensors.
Implementation Method 1
the thermally activated delayed fluorescence (TADF) material. Such a material presented a relatively good light-emitting performance
Implementation Method 2
the T1 excitons may have a reverse intersystem crossing (RISC) to achieve the T1→S1 process; and achieve a radiative decay from the S1 state to the ground state S0
Implementation Method 3
When the organic material in a light-emitting layer of an OLED is electrically activated, the singlet excitons (S1) and the triplet excitons (T1) are generated
Data Source
AI summary
The present disclosure provides a nitrogen-containing heterocyclic compound having general formula (I) and an organic photoelectric apparatus thereof.where A1, A2, A3, A4, A5, A6, A7, and A8 are independently selected from a hydrogen atom, at least one compound having the general formula (II) and at least one compound having the general formula (III),where Y1, Y2, and Y3 are independently selected from C and N; R3 and R4 are independently selected from C6-30 aromatic group and C2-30 heterocyclic aromatic group,wherein X is selected from any one of oxyl group (—O—), sulfhydryl group (—S—), substituted or non-substituted imino group, substituted or non-substituted methylene group, and substituted or non-substituted silicylene group; R5, R6, R7, R8, R9, R10, R11, and R12 are independently selected from hydrogen, deuterium, C1-30 alkyl group, C6-30 aromatic group, or C2-30 heterocyclic aromatic group.