About carrier's self-trapping and dynamical Rashba splitting in the two-dimensional hybrid perovskite (BA)$_2$(MA)$_2$Pb$_3$I$_{10}$

TL;DR

This study uses time- and angle-resolved photoelectron spectroscopy to investigate photoexcited carriers in a 2D hybrid perovskite, revealing details about band structure, effective masses, and the absence of self-trapping within 120 ps.

Contribution

It provides new insights into carrier dynamics, Rashba splitting, and exciton formation in (BA)$_2$(MA)$_2$Pb$_3$I$_{10}$, with experimental and theoretical analysis.

Findings

Effective masses for electrons and holes quantified.

Upper bound of Rashba coupling established.

No evidence of self-trapping or small polarons within 120 ps.

Abstract

Time- and Angle-Resolved Photoelectron Spectroscopy (tr-ARPES) is employed to monitor photoexcited electrons in the two-dimensional hybrid perovskite (BA)$_2$(MA)$_2$Pb$_3$I$_{10}$. Photoelectron intensity maps are in good agreement with ab-initio calculations of the band structure. The effective mass is $-0.18 \pm 0.02 m_e$ and $0.12 \pm 0.02 m_e$ for holes and electrons, respectively. In the photoexcited state, spin-orbit splitting of the conduction band cannot be resolved. This sets the upper bound of photoinduced Rashba coupling to $\alpha_C<2.5$ eV\AA. The correlated electron-hole plasma evolves in Wannier excitons with Bohr radius of 2.8 nm, while no sign of self-trapping in small polarons is found within the investigated time window of up to 120 ps following photoexcitation.