Spirobifluorene Light Emitting Material for OLED Efficiency
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Solution Overview
Problem
The development of stable and efficient organic material layer materials for organic light emitting devices has not been fully realized, limiting the full exhibition of excellent characteristics such as high brightness, efficiency, and color purity.
Innovation Solution
A novel light emitting material with a specific compound structure, represented by Formula 1, is introduced, which enhances light emission efficiency by incorporating a thiophene-substituted phenyl moiety and a 9-(2-naphthyl)anthracene moiety, allowing for improved quantum efficiency and light emitting characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a host/dopant system is used to enhance color purity and light emitting efficiency, then color purity and light emitting efficiency are improved, but device complexity increases due to the need for multiple materials and energy transfer mechanisms
Solution Approach 1:
The patent extracts and eliminates the dopant component from the host/dopant system, using only pure spirobifluorene compound as the light emitting material. This extraction maintains high light emitting efficiency and color purity while simplifying the device structure by removing the need for multiple material combinations and complex energy transfer mechanisms.
Solution Approach 2:
The patent employs a composite molecular structure within the spirobifluorene compound itself, combining multiple functional moieties (spirobifluorene core with specific substituents) into a single integrated material that provides both high efficiency and color purity without requiring separate host and dopant materials.
2Device complexity
If only one material is used for the light emitting layer, then device complexity is reduced, but light emitting efficiency and color purity deteriorate due to molecular interaction and wavelength shift
Solution Approach 1:
The patent changes the molecular parameters of the light emitting material by designing a specific spirobifluorene structure with controlled substituents (where R1-R6 are independently selected from hydrogen, deuterium, fluorine, cyanide, nitro, carboxyl, and various hydrocarbon groups). This parameter optimization allows a single material to achieve high light emitting efficiency and color purity without molecular interaction issues.
Solution Approach 2:
The patent uses a composite molecular structure within the single spirobifluorene material that integrates multiple functional characteristics, enabling one material to perform the roles previously requiring host/dopant combinations while maintaining simplicity.
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 novel structure significantly increases light emission efficiency, with the compound showing about two times stronger light emitting characteristics compared to similar structures without thiophene, enhancing the absolute light emitting efficiency of the dopant and improving the light emitting efficiency of the device.
Implementation Method 1
The organic light emitting phenomenon has a structure usually comprising an anode, a cathode, and an organic material layer interposed therebetween. When a voltage is applied between two electrodes, holes from the anode and electrons from a cathode are injected into the organic material layer, the holes and the electrons injected are combined together to form excitons. Further, when the excitons drop to a ground state, light is emitted.
Implementation Method 2
If a small amount of a dopant having a smaller energy band gap than a host forming a light emitting layer is mixed in the light emitting layer, excitons which are generated in the light emitting layer are transported to the dopant, thus emitting a light with a high efficiency. Here, since the wavelength of the host is moved into the wavelength range of the dopant, a light having a desired wavelength can be obtained according to the kind of the dopant.
Data Source
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AI summary
The present invention provides a novel light emitting material and an organic light emitting device using the same.