Photophysics of two-dimensional perovskites -- learning from metal halide substitution

Abstract

Whereas their photophysics exhibits an intricate interplay of carriers with the lattice, most reports have so far relied on single compound studies. With the exception of variations of the organic spacer cations, the effect of constituent substitution on the photophysics and the nature of emitting species, in particular, has remained largely under-explored. Here PEA${}_2$PbBr${}_4$, PEA${}_2$PbI${}_4$, and PEA${}_2$SnI${}_4$ are studied through a variety of optical spectroscopy techniques to reveal a complex set of excitonic transitions at low temperature. We attribute the emergence of weak high energy features to a vibronic progression breaking Kasha's rule and highlight that the responsible phonons cannot be accessed through simple Raman spectroscopy. Bright peaks at lower energy are due to two distinct excitons, of which the upper is a convolution of a bright exciton and a localised state, whereas the lower is attributed to shallow defects. Our study offers deeper insights into the photophysics of two-dimensional perovskites through compositional substitution and highlights critical limits to the communities' current understanding of the photophysics of these compounds.

References in corpus (3)

• Database of 2D hybrid perovskite materials: open-access collection of crystal structures, band gaps and atomic partial charges predicted by machine learning
• Directional Anisotropy of the Vibrational Modes in 2D Layered Perovskites
• Tailoring Hot Exciton Dynamics in 2D Hybrid Perovskites through Cation Modification

Cited by in corpus (5)

• Coherent Spin Dynamics of Electrons in Two-Dimensional (PEA)${}_2$PbI${}_4$ Perovskites
• Influence of Organic Spacer Cation on Dark Excitons in 2D Perovskites
• Many-Exciton Quantum Dynamics in a Ruddlesden-Popper Tin Iodide
• Engineering Dion-Jacobson Perovskites in Polariton Waveguides
• Material gain and eight-band k.p description for selected perovskites