[ Instrument network instrument research and development ] Recently, Han Keli team, researcher of complex molecular system reaction kinetics research group of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, revealed the dynamic mechanism of non-lead sodium-indium-based double perovskite nanocrystals. The team innovatively synthesized undoped and silver-doped non-lead double perovskite nanocrystals by variable temperature thermal injection. The silver-doped nanocrystals exhibited bright yellow fluorescence and discussed their self-trapping in detail. Sub-luminescence dynamics mechanism.
Non-lead perovskite nanocrystals have attracted people's attention due to their non-toxicity and stability, and have become a hot spot in current research. In particular, indium-based double perovskite nanocrystals having a three-dimensional structure and a direct band gap are considered to be ideal luminescent materials and are expected to be used in the field of illumination. At present, the fluorescence quantum yield of undoped indium-based nanocrystals is still very low, which has not reached people's expectations. It is mainly because the mechanism is unclear, which restricts the design and development of new and efficient perovskite materials. the study.
In this work, the team innovatively synthesized high-quality undoped and silver-doped direct band gap sodium-indium-based non-lead double perovskite nanocrystals using a variable temperature hot injection method. The synthesis of mineral nanocrystals is universal. It is found that the undoped Cs2NaInCl6 nanocrystals have almost no fluorescence. The reason why the non-fluorescence is proved by the femtosecond transient absorption technique is that the self-trapped excitons are dark and tend to be non-radiative. The researchers also found that by doping a small amount of silver, it can not only break the undoped Cs2NaInCl6 nanocrystalline dark state self-trapped excitons, transforming them into bright self-trapped excitons, but also passivating the defects of nanocrystals. Therefore, Cs2NaInCl6: Ag nanocrystals exhibit bright yellow light and better stability, and the fluorescence quantum yield is as high as 31.1%. The mechanism of the self-trapped exciton is further studied by time-resolved fluorescence and femtosecond transient absorption techniques. . This work emphasizes the importance of synthetic method optimization and proper element doping for the design of new semiconductor materials, and provides a new feasible way to find new high-performance nano materials in the field of optoelectronics.
The above work was funded by the National Natural Science Foundation of China and was recently published in Angew. Chem. Int. Ed.
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