Rapid Spin Depolarization in the Layered 2D Ruddlesden-Popper Perovskite (BA)(MA)PbI.

Kempf, Michael Andreas; Moser, Philipp; Tomoscheit, Maximilian; Schröer, Julian; Blancon, Jean-Christophe; Schwartz, Rico; Deb, Swarup; Mohite, Aditya et al. · ACS Nano · 2023

basic_science · Level V

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Abstract

We report temperature-dependent spectroscopy on the layered (<i>n</i> = 4) two-dimensional (2D) Ruddlesden-Popper perovskite (BA)(MA)PbI. Helicity-resolved steady-state photoluminescence (PL) reveals no optical degree of polarization. Time-resolved PL shows a photocarrier lifetime on the order of nanoseconds. From simultaneously recorded time-resolved differential reflectivity (TRΔR) and time-resolved Kerr ellipticity (TRKE), a photocarrier lifetime of a few nanoseconds and a spin relaxation time on the order of picoseconds was found. This stark contrast in lifetimes clearly explains the lack of spin polarization in steady-state PL. While we observe clear temperature-dependent effects on the PL dynamics that can be related to structural dynamics, spin relaxation is nearly <i>T</i>-independent. Our results highlight that spin relaxation in 2D (BA)(MA)PbI occurs at time scales faster than the exciton recombination time, which poses a bottleneck for applications aiming to utilize this degree of freedom.