Tsinghua University has made a major breakthrough in the research and development of blue light organic light-emitting diode technology!
Introduction. With the rapid development of modern science and technology, as well as the rapid development of various electronic devices, the performance of the display has been greatly improved. Organic light-emitting devices (OLEDS) are widely used in smartphones, tablets, and televisions due to their self-luminescence, high quality, ultra-thinness, and flexibility. Efficient and stable blue light-emitting materials are the core of OLED, but there are still problems such as low luminous efficiency and poor stability. However, the blue OLED devices currently used in commercial use have problems such as low conversion efficiency and low service life, and there is an urgent need to further improve the process level.
Scientific and technological progress. In the State Key Laboratory of "Organic Optoelectronics and Molecular Engineering", the research group of Lian Duan and Dongdong Zhang has made a major breakthrough in blue OLED. The applicant took the lead in the world to achieve the high efficiency, stability and stability of TADF Blu-ray OLED by replacing the deuterium generation. Replacing all the hydrogen atoms in Tadf with deuterium can significantly inhibit the high-frequency oscillation of Tadf, thereby reducing the radiation-free jump rate and reducing the dissociation probability of chemical bonds. On this basis, by changing the luminescence wavelength of the solid material, the luminescence range is narrowed, so as to obtain high color pure blue light emission.
In this project, the whole Tadf compound is prepared by multiplex hydrothermal method. Compared with non-tritium small molecules, *s has a higher external quantum efficiency and a higher operating lifetime. The external quantum efficiency of the device is 331% with 1365 hours of device use. In the previous work, the applicant's research group found that the luminescence quantum yield, photochemical stability, and fluorescence resonance energy transfer efficiency of **s have been greatly improved through the study of the photophysical properties of **s, mainly due to the high frequency oscillation of **s in **s and the redistribution of energy levels of **s in **s.
Prospects for the use of technology.
This project will provide a new theoretical basis for the structure and performance control of TADF materials, and provide a new idea for the realization of high-efficiency and high-stability blue OLEDS. Therefore, this project intends to carry out research on blue thermal delay fluorescent materials based on TADF. At present, the commercialized blue OLED is dominated by phosphorescent luminescence, and thermal delayed fluorescence (TADF) has the characteristics of high-efficiency luminescence, which has aroused great interest. However, there are major problems with thermally delayed fluorescence (TADF), especially in the blue light region. Therefore, in future research, how to screen out better Tadf materials to better improve their stability is an important topic facing the current academic and industrial circles.
Personal Summary. From this study, we can see that in the blue light OLED technology, the Tsinghua research group has achieved a major breakthrough by using the method of pure deuterium substitution. On this basis, we have made a breakthrough in TADF materials and obtained excellent performance that is superior to that of commercial blue light OLED. The implementation of this project will provide theoretical basis and technical support for promoting the development of OLED technology and the industrialization of Blu-ray TADF.
However, this method needs to be further studied and improved. Firstly, according to the stability of thermally delayed fluorescent materials, suitable light-emitting devices were screened and optimized to improve their stability in the blue band. Secondly, further improve the preparation technology and technology of **s, and improve the efficiency and scale of **s. At the same time, it is also necessary to strengthen close cooperation with the industrial circles to promote the industrialization process of this technology, promote its popularization in the field of electronics, and improve production efficiency.
Our research group has made an important breakthrough in the research of blue light OLEDS, and the conversion efficiency and service life of TADF OLEDs have been achieved by using the complete deuterium substitution method. The implementation of this project will provide new ideas for the preparation of efficient and stable blue light OLED, and will play a positive role in promoting the development and industrial application of OLED. In the future, this technology will be used more and more in various electrical appliances, making our lives more convenient and amazing.