All-Organic Phosphorescent Compound for OLED Efficiency
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Solution Overview
Problem
Conventional organic compounds used in OLEDs have limitations such as low triplet energy levels, short luminous lifetimes, and limited thermal stability, which hinder their application in commercial devices due to issues with exciton confinement and non-radiative recombination.
Innovation Solution
An organic compound with a carbazole moiety and dibenzofuran or dibenzothiophene moieties linked to a central five-member fused heteroaromatic linker, providing high excited triplet energy and bipolar properties, is developed to enhance thermal stability and prevent non-radiative recombination in OLEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional phosphorescent materials with metal complexes are used to increase luminous efficiency by involving triplet excitons, then luminous efficiency is improved, but luminous lifetime becomes too short for commercial application
Solution Approach 1:
The patent changes the chemical composition parameters by replacing metal complex phosphorescent materials with all-organic phosphorescent compounds containing boron, nitrogen, and oxygen atoms. This parameter change maintains high luminous efficiency through triplet exciton involvement while extending luminous lifetime to be suitable for commercial applications, as the organic compounds exhibit both high efficiency and appropriate lifetime characteristics.
2Temperature
If organic aromatic compounds with increased conjugated structure or fused rings are used to raise triplet energy level above phosphorescent dopant, then triplet energy level is improved, but the number of available compounds is severely limited
Solution Approach 1:
The patent employs composite material design by combining boron, nitrogen, and oxygen atoms in specific molecular configurations to create all-organic phosphorescent compounds. This composite approach achieves the required triplet energy level (higher than phosphorescent dopant) while providing a versatile class of compounds with various structural possibilities, thus resolving the limitation of available host compounds.
3Device complexity
If conventional fluorescent materials are used to simplify the luminescence process by involving only singlet excitons, then device complexity is reduced, but luminous efficiency becomes too low for commercial use
Solution Approach 1:
The patent introduces all-organic phosphorescent compounds as intermediaries that facilitate the involvement of triplet excitons in the luminescence process. These compounds act as mediators between the electrical charges and light emission, enabling efficient triplet exciton utilization while maintaining a relatively simple device structure, thus resolving the contradiction between complexity and efficiency.
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 organic compound improves luminous efficiency, extends the OLED's lifetime by efficient exciton confinement and energy transfer, and reduces the risk of degradation from Joule's heat, leading to enhanced performance and longevity of OLEDs.
Implementation Method 1
the phosphorescent host should have triplet energy higher than the phosphorescent dopant in order to prevent the triplet energy of the phosphorescent dopant from transferring to the host
Implementation Method 2
efficient exciton confinement and energy transfer
Data Source
AI summary
The present disclosure relates to an organic compound having the following structure of Chemical Formula 1, and an organic light emitting diode (OLED) and an organic light emitting device including the organic compound. The organic compound is a bipolar organic compound having a p-type moiety and an n-type moiety. The organic compound has a high excited triplet energy level, a wide energy bandgap and excellent thermal stability. When the organic compound is introduced into an emitting material layer (EML) of the OLED, holes and electrons are recombined in the whole area of the EML, thus the OLED can improve its luminous efficiency and luminous lifetime.