Organic-inorganic hybrid metal halide perovskites (MHPs) have attracted tremendous attention for optoelectronic applications. For example, cost-effective solar cells, solid-state lighting, memristors and ultra-fast spin switches in spintronics have recently been designed using MHPs. Despite the promise of the material, many questions remain about the nature and mobility of charge carriers in MHPs, which require more understanding.

Researchers from Shanghai University of Science and Technology, in collaboration with the Qingdao Institute of Bioenergy and Bioprocess Technology, Shanghai University, Shanghai Institute of Technical Physics, Shanghai Jiao Tong University and Lomonosov Moscow State University, are now reporting photoinduced large polaron transport and dynamics in organic-inorganic hybrid lead halide perovskite with terahertz probes.

The researchers experimentally identify the photocarrier-optical phonon coupling in CH3NH3PbI3 (MAPbI3) polycrystalline grains, using optical pump and terahertz electromagnetic probe spectroscopy. The photoinduced charge carrier together with the surrounding lattice distortion over different lattice constants forms a quasi-particle – a polaron. Using the Drude-Smith-Lorentz model along with the Frӧhlich-type electron-phonon coupling, the researchers determine the effective mass and scattering parameters of photogenerated polaronic carriers. According to the polaron mass increase, the polycrystalline nature of the material and the presence of defects, the large polaron mobility is calculated on the order of ~80 cm2V−1s−1†

Furthermore, the researchers reveal that the formation of large polarons in MAPbI3 protects the charge carriers from scattering with polycrystalline grain boundaries or defects and explains the long life of photoconductivity. The findings provide insight into the polaronic nature of charge carriers in MAPbI3 materials, which is relevant for both basic research and device applications. The results will be published in the journal Light: Science and Applications†

Shining light on excited state dynamics in perovskite materials

Detailed information:
Zuanming Jin et al, Photoinduced large polaron transport and dynamics in organic-inorganic hybrid lead halide perovskite with terahertz probes, Light: Science and Applications (2022). DOI: 10.1038/s41377-022-00872-y. Provided by the Chinese Academy of Sciences