Pressure-Induced Disorder-to-Order Transition in Pb2SbS2I3 Enhances Photoelectric Response.

Abstract

Mixed-anion chalcogenide compounds, particularly Pb2SbS2I3, hold promise for optoelectronic applications owing to their chemical stability and tunable electronic properties. However, their performance is intrinsically limited by disordered polyhedral connectivity and native defects inherent to sulfohalide structures, which is challenging to optimize through conventional chemical methods. Here, a high-pressure strategy is employed to drive a structural transition from the distorted orthorhombic Cmcm phase to an ordered monoclinic P21/c phase at ∼6.3 GPa. Electronic structure calculations reveal that pressure-induced ordering of [PbS4I2]4- and [SbI6]3- polyhedra enhances light absorption, reduces electron effective mass, and promotes carrier delocalization. Consequently, under high-pressure conditions, the photocurrent density and responsivity both increased by more than four orders of magnitude, while the specific detectivity was enhanced by more than one order of magnitude. This pressure-mediated disorder-to-order transition optimizes the electronic structure, concomitantly enhancing its photoelectric response. Our findings highlight the potential of pressure engineering as a promising strategy for regulating structure-property relationships in mixed-anion materials, offering a pathway to design high-performance photodetectors for extreme-condition applications.