Pressure Regulation of the Lone-Pair 5s² Electrons in Metal Phosphorous Chalcogenides SnPS₃ for Enhanced...

Lone-pair ns² electrons play a key role in designing high performance optoelectronic semiconductors, such as metal phosphorous chalcogenides (MPChs), for photoelectric detection technologies. However, how to regulate lone-pair ns² electrons for superior properties attracts wide attention and are still major concerns for MPChs. Herein, we presented a lone-pair-electron regulation strategy to significantly enhance the photoelectric properties of SnPS₃ by pressure-induced overlapping of lone-pair electrons of Sn²⁺ and non-bonding electrons of S^2-. As a result, the photocurrent density, responsivity, and external quantum efficiency of the SnPS₃ material were strikingly improved by five orders of magnitude compared to those at ambient pressure. A synergistic theoretical and experimental characterizations indicate that pressure triggers the overlapping of lone-pair 5s² electrons of Sn²⁺ and non-bonding electrons of sulfur, resulting in a hybrid orbital transition instead of a p-p orbital transition, which results in high light absorption capability and low effective mass, and thus better photoelectronic properties. These findings provide an effective pressure engineering strategy to optimize the performance of photodetectors by regulating lone-pair ns² electrons and highlight the potential of Sn instead of Pb for the development of advanced photoelectric devices.