TADF Host Material for Shared Blue OLED Spectrum Purity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The range of applicable luminescent materials in organic electroluminescent display devices with a shared blue light layer is limited, and existing technologies face challenges with process complexity, reliability, and display quality due to the need for precise layering and individual driving circuits.
Innovation Solution
An organic electroluminescent device with a shared blue light layer that incorporates Thermal Activation Delayed Fluorescence (TADF) materials in the green light units, allowing for a broader range of luminescent material combinations without blue light in the red/green subpixels' spectra, eliminating the need for a hole-blocking layer and simplifying the device structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared blue light layer is used in organic electroluminescent display devices, then the device structure is simplified and production cost is reduced, but the range of applicable luminescent materials is limited
Solution Approach 1:
The patent changes the energy level parameter of the hole-blocking layer material to greater than 5.5 eV, which resolves the material selection limitation while maintaining the shared blue light layer structure simplification
Solution Approach 2:
The patent uses composite material design by combining specific host materials (mCP, TCTA, TAPC) with guest materials (Alq3, BCP) in the hole-blocking layer to achieve both structural simplification and broad material applicability
2Ease of manufacture
If the HOMO energy level of blue light material is limited to not lower than 5.5 eV to prevent blue light component in red and green subpixels, then the light spectrum purity is improved, but the selection range of blue light material is considerably limited
Solution Approach 1:
The patent changes the energy level parameter specification from 'not lower than 5.5 eV' to 'greater than 5.5 eV' for the hole-blocking layer, which subtly adjusts the parameter range to enable broader material selection while maintaining spectrum purity
Solution Approach 2:
The patent introduces a specifically designed hole-blocking layer as an intermediary between the blue light layer and red/green subpixels, which mediates the energy level interaction to prevent blue light leakage while allowing broader material selection
3Manufacturing precision
If a hole-blocking layer with adapted energy level is provided to ensure carrier recombination in the light-emitting layer, then the display quality is improved, but the process difficulty and device complexity increase
Solution Approach 1:
The patent designs the hole-blocking layer with multi-functionality, serving both as an energy level barrier to control carrier recombination and as a bridge layer that simplifies the overall device structure, thereby improving display quality without proportionally increasing complexity
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
This approach broadens the range of applicable luminescent materials, improves display performance, reduces process complexity, and lowers production costs by eliminating the need for a hole-blocking layer and simplifying the device structure, while maintaining high efficiency and reliability.
Implementation Method 1
the host material at least includes a Thermal Activation Delayed Fluorescence (TADF) material having an energy level difference ΔEST that is less than 0.15 eV between triplet state and singlet state
Implementation Method 2
Organic Light-Emitting Devices (OLED) adopts organic electroluminescent material and is a type of active light-emitting device
Data Source
AI summary
An organic electroluminescent device adopts a TADF material as a first host material (6) of a green light unit (302) to sensitize a green phosphorescent material serving as a first guest material (7). A portion of triplet excitons are converted into singlet excitons through inverse gap crossing, and thus decrease of the triplet exciton concentration results in narrowing of the recombination region, thereby preventing the triplet excitons from diffusing into a blue light layer (4) to emit light, so as to realize a green light spectrum containing no blue light component. And because an energy level difference between red light and blue light is relatively large, carriers in a red light unit cannot be easily transferred to the blue light layer, and therefore it is not easy for a blue light component to appear in a red light spectrum. Accordingly, the light-emitting spectrums of red/green subpixels in the organic electroluminescent device with a shared blue light layer do not contain blue light, thereby effectively broaden the range of applicable combinations of luminescent materials and improving the display performance of the device. Moreover, a hole-blocking layer is not required, and thus the structure of the device is effectively simplified, and the operation voltage is lowered; in the meantime, the process difficulty is reduced, and the product yield is increased, thereby reducing the production cost.