Thermally Activated Delayed Fluorescent Polymer for OLED Efficiency
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Solution Overview
Problem
Conventional thermally activated delayed fluorescent polymer materials have low photoluminescence quantum yield and small reverse intersystem crossing constants, leading to low external quantum efficiency in OLED light-emitting devices.
Innovation Solution
A synthesizing method for a thermally activated delayed fluorescent material involving a series of heating and high-pressure reactions with specific catalysts and monomers, such as tert-butylcarbazole, 4-bromo-diphenylsulfone chain styrene, and phenoxazine, to produce a polymer with high luminous efficiency by connecting red, green, and blue light-emitting units to polystyrene side chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If thermally activated delayed fluorescent polymer material is used, then wet processing capability and film-forming property are improved, but photoluminescence quantum yield and reverse intersystem crossing constant are reduced
Solution Approach 1:
The patent introduces a rigid rod segment (1,4-phenylene or 1,3-phenylene group) as a localized structural unit within the polymer chain. This rigid segment specifically targets and controls the molecular packing and aggregation behavior in the solid state, thereby locally optimizing the photoluminescence quantum yield and reverse intersystem crossing constant without compromising the overall polymer's wet processing capability
Solution Approach 2:
The patent creates a composite molecular structure by combining flexible chain segments (providing good film-forming property) with rigid rod segments (providing high photoluminescence quantum yield). The flexible chain segment contains carbazole or phenoxazine units while the rigid rod segment contains 1,4-phenylene or 1,3-phenylene groups, forming a hybrid polymer that achieves both processability and high efficiency
2Ease of manufacture
If conventional thermally activated delayed fluorescent polymer material is used, then manufacturing cost is reduced, but external quantum efficiency of OLED device is reduced
Solution Approach 1:
The patent modifies the molecular parameters of the polymer by incorporating rigid rod segments with specific aromatic structures (1,4-phenylene or 1,3-phenylene groups). This structural parameter change increases the reverse intersystem crossing constant and photoluminescence quantum yield, thereby improving external quantum efficiency while maintaining the polymer's cost-effectiveness and ease of manufacture
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 method results in a white light polymer material with high luminous efficiency, enhancing the lifespan and light-emitting performance of OLED devices with improved external quantum efficiency.
Implementation Method 1
a first catalyst, wherein the first catalyst is a mixture of cesium carbonate, cuprous iodide, 18-crown-6 ether, and N,N'-dimethylpropylene urea
Implementation Method 2
the triplet-excited excitons is returned to the singlet state by thermal activation, and then the single-excited excitons are radiated transitionally back to a ground state to luminescence
Implementation Method 3
a quantum efficiency of the devices prepared by the thermally activated delayed fluorescent polymer material is relatively low
Data Source
AI summary
A thermally activated delayed fluorescent material and a synthesizing method thereof are described. The thermally activated delayed fluorescent material has a structural formula as follows:Group A, group B, group C, and group D are all structural groups in the thermally activated delayed fluorescent material, where x, y, and z are molar ratios of the group B, the group C and the group D in the thermally activated delayed fluorescent material, respectively. A white light polymer material with high luminous efficiency is synthesized by using polystyrene as a main chain, and connecting red, green, and blue light-emitting structural units to side chains thereof. An OLED light-emitting layer prepared by using the thermally activated delayed fluorescent material has relatively high lifespan and good light-emitting performance.