The team of Professor Li Feng from the State Key Laboratory of Supramolecular Structures and Materials, College of Chemistry, Jilin University, used organic light-emitting radical materials to prepare organic light-emitting diodes, achieving quantum efficiency close to 100%, and solving the low luminous efficiency of traditional fluorescent materials. problem. The achievement was published in Nature at the first completion unit of Jilin University.
Light-emitting devices are key components in the field of display and illumination. Compared with traditional light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs) have the advantages of high contrast, ultra-thinness and flexibility, etc. The lighting field has great market value and application prospects. When the traditional organic light-emitting diode is energized, only 25% of the energy can be used for illuminating. How to convert most of the energy into photon luminescence has been a hotspot and a difficult point in the research field for nearly 30 years.
The research team found that organic light-emitting radicals with a unique single-electron structure generate only doublet excitons when energized. Theoretically, 100% of doublet excitons can be used for luminescence. The organic light-emitting diode is prepared by using an organic light-emitting radical material, which can solve the problem that the traditional organic light-emitting diode has low luminous efficiency. Through continuous improvement of materials and device structure, the team has developed high luminous efficiency free radical luminescent materials and light-emitting devices.
Li Feng introduced that the luminescent materials currently used in organic light-emitting diodes are usually fluorescent and phosphorescent materials, but the former has limited luminous efficiency, while the latter requires heavy metals with scarce resources, resulting in higher costs. In contrast, organic radical materials are inexpensive organic compounds that reduce costs after maximizing the efficiency of electrorotation.
The research was supported by the National Natural Science Foundation of China, the Key Research and Development Program of the Ministry of Science and Technology, the 973 Program, the Visiting Scholars Program of the China Scholarship Council, and the Pei Ying Project of Jilin University.
Li Feng told reporters that the importance of this research is mainly to scientifically confirm that the luminescent free radical is doublet luminescence – a new electroluminescence principle, and can achieve 100% of the luminescent device. Quantum efficiency, but there is still a certain distance from actual production and life. It is also necessary to expand the material system of luminescent free radicals to achieve different color luminescence and improve the stability of luminescent free radicals.
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