In-situ observation of trapped carriers in organic metal halide perovskite films with ultra-fast temporal and ultra-high energetic resolutions.

Autor: Kobbekaduwa, Kanishka, Shrestha, Shreetu, Adhikari, Pan, Liu, Exian, Coleman, Lawrence, Zhang, Jianbing, Shi, Ying, Zhou, Yuanyuan, Bekenstein, Yehonadav, Yan, Feng, Rao, Apparao M., Tsai, Hsinhan, Beard, Matthew C., Nie, Wanyi, Gao, Jianbo
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Zdroj: Nature Communications; 3/12/2021, Vol. 12 Issue 1, p1-7, 7p
Abstrakt: We in-situ observe the ultrafast dynamics of trapped carriers in organic methyl ammonium lead halide perovskite thin films by ultrafast photocurrent spectroscopy with a sub-25 picosecond time resolution. Upon ultrafast laser excitation, trapped carriers follow a phonon assisted tunneling mechanism and a hopping transport mechanism along ultra-shallow to shallow trap states ranging from 1.72–11.51 millielectronvolts and is demonstrated by time-dependent and independent activation energies. Using temperature as an energetic ruler, we map trap states with ultra-high energy resolution down to < 0.01 millielectronvolt. In addition to carrier mobility of ~4 cm2V−1s−1 and lifetime of ~1 nanosecond, we validate the above transport mechanisms by highlighting trap state dynamics, including trapping rates, de-trapping rates and trap properties, such as trap density, trap levels, and capture-cross sections. In this work we establish a foundation for trap dynamics in high defect-tolerant perovskites with ultra-fast temporal and ultra-high energetic resolution. Defect states in perovskites dictate the charge carriers behaviour, thus the ultimate optical and electrical properties. Here, the authors in-situ investigate trapped carrier dynamics in MAPbI3 thin films with ultra-fast temporal and high energetic resolution by means of ultrafast photocurrent spectroscopy. [ABSTRACT FROM AUTHOR]
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