Co-Host Material Composition for Blue TADF Emitting Layers
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Solution Overview
Problem
Conventional light emitting devices using exciplex as host material face limitations in selecting thermally activated delayed fluorescent materials and struggle to produce blue light emitting layers due to restricted emission spectrum and energy band gap constraints.
Innovation Solution
A co-host material comprising a first compound and a second compound, specifically designed to satisfy energy level relationships and avoid exciplex formation, is used to create a non-exciplex bipolar composite material, which is mixed with thermally activated delayed fluorescent materials to form a light emitting layer suitable for blue light emitting devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If exciplex is used as host material, then device structure is simplified, but selection of thermally activated delayed fluorescent material is limited and blue light emission is difficult to achieve
Solution Approach 1:
The patent uses a composite host material system consisting of a non-exciplex bipolar compound combined with a unipolar compound. This composite approach allows the system to maintain simplified structure while expanding the selection range of thermally activated delayed fluorescent materials and enabling blue light emission, thereby resolving the contradiction between device simplicity and material versatility.
2Ease of manufacture
If exciplex host material is used, then device fabrication is simplified, but emission spectrum is restricted and energy band gap constraints prevent blue light emission
Solution Approach 1:
The patent changes the energy level parameters of the host material system by using a non-exciplex bipolar compound with specific HOMO and LUMO levels combined with a unipolar compound. This parameter adjustment expands the emission spectrum range and enables blue light emission while maintaining ease of fabrication through conventional OLED manufacturing processes.
3Ease of operation
If conventional host material is used, then material selection is straightforward, but thermally activated delayed fluorescent material selection is limited
Solution Approach 1:
The patent segments the host material function into two parts: a non-exciplex bipolar compound that provides the fundamental host properties and a unipolar compound that expands the emission spectrum. This segmentation allows for straightforward material selection based on individual compound properties while achieving versatile thermally activated delayed fluorescent material compatibility and blue light emission.
Data Source
AI summary
The present disclosure provides a co-host material, a composition for forming a light emitting layer, and a light emitting device. The co-host material can at least partially solve the difficulty in the limited selection of thermally activated delayed fluorescent materials in the existing light emitting devices, and the difficulty in providing a light emitting layer of a blue light emitting device. The co-host material comprises a first compound and a second compound each having a specific general formula.