Charge Carrier Dynamics in Two-Dimensional Hybrid Perovskites: Impact of Spacer Cations

Two-dimensional (2D) halide perovskites are promising materials for environmentally stable next-generation optoelectronic devices. However, there is very little atomistic understanding of the charge carrier dynamics at ambient conditions for these materials. Here, by combining nonadiabatic molecular dynamics with time-domain density functional theory methods at room temperature, we study the dominant non-radiative carrier recombination and dephasing processes in monolayered lead halide perovskites. Our systematic study demonstrates that performance-limiting nonradiative carrier recombination processes greatly depend on the electron-phonon interactions induced by structural fluctuations and instantaneous charge localization in these materials. The stiffer interlayer packing in presence of selectively chosen spacer cations (benzene ring/cyclic dication based), which separates the lead iodide slabs, reduces the thermal fluctuations in these 2D-perovskites to a greater extent.[1-2] These reduce the inelastic electron-phonon scattering and enhance the photogenerated charge carrier lifetime in layered perovskites making them suitable for various optoelectronic devices.

1. Ghosh et al. J. Phys. Chem. Lett, 2020, 11, 2955
2. Ghosh et al. J. Mater. Chem. A, 2020 (DOI: 10.1039/D0TA07205B)