About Carrier's Self-Trapping and Dynamical Rashba Splitting in the 2D Hybrid Perovskite (BA)2(MA)2Pb3l10.

Time- and Angle-Resolved Photoelectron Spectroscopy (tr-ARPES) is employed to monitor photoexcited electrons in the 2D hybrid perovskite (BA) 2 $_2$ (MA) 2 Pb $_2{\rm Pb}$ 3 I $_3{\rm I}$ 10 $_{10}$ . Photoelectron intensity maps are in good agreement with ab-initio calculations of the band structure. The effective mass is - 0.18 ± 0.02 m 0 $-0.18 \pm 0.02 m_0$ and 0.12 ± 0.02 m 0 $0.12 \pm 0.02 m_0$ 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 α C < 2.5 $\alpha _C<2.5$ eVÅ. 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.