Recently, the team of Han Keli, a researcher at the Dalian Institute of Chemical Physics, Chinese Academy of Sciences, and Professor Tonu Pullerits of Lund University in Sweden and others have made new progress in the study of perovskite microcrystalline photocurrent imaging. "(The Journal of Physical Chemistry Letters).
In recent years, perovskite materials have been widely used in research fields such as solar cells, photodetectors, and luminous displays, and have made a series of breakthroughs. The good performance of perovskite mainly comes from its excellent carrier characteristics, such as high carrier mobility and long diffusion length. However, the microscopic carrier dynamic behavior of perovskite devices under real working conditions is still unclear.
Recently, the team successfully prepared a CH3NH3PbBr3 perovskite microcrystalline photodetector, and used high spatial resolution (1 micron, 1 micron = 10-6 meters) photocurrent imaging technology to study its carrier under an applied electric field. Dynamic behavior. The study found that under a weak electric field, the carrier transport is a diffusion mechanism (diffusion); under a stronger electric field, the carrier transport is a migration mechanism (drift), and the carrier transport length is positive to the applied electric field strength Related. In addition, the study also found that in the CH3NH3PbBr3 perovskite single crystal, the distribution of defect states is also uneven, and affects the carrier transport length, which in turn affects device efficiency. This result indicates that the overall efficiency of the device can be improved by better controlling the distribution of defect states in the single crystal.
The above work was supported by key projects of the National Natural Science Foundation of China.
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