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

Abstract

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 similar to 4 cm(2)V(-1)s(-1) and lifetime of similar to 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.

Description
Keywords
LIGHT-EMITTING-DIODES, CHARGE-TRANSPORT, SOLAR-CELLS, DEEP LEVELS, RECOMBINATION, CONDUCTIVITY, DEGRADATION, MECHANISM, JUNCTIONS, DYNAMICS, Multidisciplinary Sciences
Citation
Kobbekaduwa, K., Shrestha, S., Adhikari, P., Liu, E., Coleman, L., Zhang, J., Shi, Y., Zhou, Y., Bekenstein, Y., Yan, F., Rao, A. M., Tsai, H., Beard, M. C., Nie, W., & Gao, J. (2021). In-situ observation of trapped carriers in organic metal halide perovskite films with ultra-fast temporal and ultra-high energetic resolutions. In Nature Communications (Vol. 12, Issue 1). Springer Science and Business Media LLC. https://doi.org/10.1038/s41467-021-21946-2