Self-Trapped Exciton Emission in a Zero-Dimensional (TMA)2SbCl5·DMF Single Crystal and Molecular Dynamics Simulation of Structural Stability

Lead-free lower-dimensional organic–inorganic metal halide materials have recently triggered intense research because of their excellent photophysical properties and chemical stability. Herein, we report a novel zero-dimensional (0D) organic–inorganic hybrid single crystal (TMA)2SbCl5·DMF (TMA = N(CH3)3, DMF= HCON(CH3)2), which exhibits typical self-trapped exciton (STE) emission with an efficient yellow emission at 630 nm and high photoluminescence quantum yield (PLQY) of 67.2%. The dual STE emission is attributed to the singlet and triplet STEs in inorganic SbCl52–, respectively. Further, an ab initio molecular dynamics simulation was performed to estimate the stability of crystal structure at room temperature. The calculated excited-state structure indicates that the deformation parameter (Δd) of the excited-state structure is larger than that of the ground state, illustrating the origin of a large Stokes shift. These results indicate that these new 0D lead-free organic–inorganic hybrid metal halides are promising luminescent materials for optoelectronic applications.