Tunable optical and scintillation properties of two-dimensional tin-mixed halide perovskites

Abstract

Controllable doping of hybrid organic-inorganic perovskites (HOIPs) fueled strong interest towards their utilization as a scintillating material. In terms of cationic engineering, tin-mixed halides perovskite (TMHP) is considered as a stronger contender than the conventional hybrid perovskite counterparts. However, the lack of physicochemical alteration via simultaneous A- site and X-site substitution remains unresolved to date. In this work, we tailor both organic ligand and halide mixture of TMHPs to shed some light on their optical and scintillation properties. By introducing three organic ligands, we synthesize phenylmethylammonium (PMA), phenethylammonium (PEA) and phenylpropylammonium (PPA) and retain the Br: I ratio at 3:1. In terms of structural order, we find that the interlayer spacing between the inorganic layers is gradually extended from 9.88 Å for (PMA)₂SnBr₃I, 10.29 Å (PEA)₂SnBr₃I, to 10.06 Å for (PPA)₂SnBr₃I. In combination with geometrical orders organic chain penetration and octahedra distortion angle, we propose a rational design to modulate the absorption, photoluminescence (PL), optical bandgap, and thermal quenching of TMHPs. (PMA)₂SnBr₃I exhibit a fastest decay time (τavg = 1.1 ns) than the (PEA)₂SnBr₃I (τ_avg= 2.51 ns) and (PPA)₂SnBr₃I (τ_avg = 3.54 ns), indicating that TMHPs are promising candidates for scintillator applications. The finding is corroborated by density functional theory to outline the weakened antibonding interaction between I 5p and Sn 5s orbitals upon tailoring the organic ligand of the perovskite. Our attempt demonstrates the importance of cation-engineering in leveraging innovative hybrid perovskites with novel response via rational design.