Self‐Trapped Excitons in 2D SnP₂S₆ Crystal with Intrinsic Structural Distortion

Abstract

Abstract Exploring and utilizing novel materials with self‐trapped excitons (STEs) is highly desired due to their unique physical properties and multiple optoelectronic applications. Here, a 2D SnP 2 S 6 crystal is reported with obvious STEs emission caused by distorted [SnS 6 ] 8‐ and [P 2 S 6 ] 4‐ octahedral units and strong electron‐phonon coupling. The STEs feature wide photoluminescence (PL) spectra range from 600 to 850 nm and a large Stokes redshift of ≈0.6 eV. Carrier dynamics measurements including temperature‐dependent PL and transient absorption reveal a large Huang–Rhys factor of ≈18.3 and a self‐trapping process of ≈10 1 –10 3 ps in the 2D SnP 2 S 6 crystal. Such self‐trapped states enable 2D SnP 2 S 6 crystal a wide spectral response range and excellent photodetection performance. As a result, high responsivity (22.8 A W ‐1 ) and detectivity (3.98 × 10 10 Jones) are achieved under 365 nm light illumination. These results provide a deep insight into the photophysical process of STEs, which lays the foundation for developing novel STEs‐based materials and optoelectronic devices.