MXenes as bipolar transport layer on the performance of SnS-based piezophototronic photodetector

The performance of photodetectors can be significantly enhanced by incorporating a suitable transport layer, where the work function and density of states (DOS) are critical parameters in material selection. MXenes, with their tunable work functions, offer versatility for integrating diverse active materials in device architectures. In this work, we investigate the photodetection performance and piezophototronic effect of three tin monosulfide (SnS)-based device configurations, validated through band structure analysis. SnS was integrated with Ti₃C₂Tₓ and Mo₂TiC₂Tₓ MXenes and benchmarked against a reference SnS/Ag device. The fabricated devices—SnS, SnS/Ti₃C₂Tₓ, and SnS/Mo₂TiC₂Tₓ—exhibited responsivities of 7.67 A/W (5.86 A/W), 15.07 A/W (12.41 A/W), and 89.23 A/W (57.42 A/W) with (without) strain, respectively. Density functional theory calculations revealed enhanced DOS at the Fermi level for both MXenes, highlighting their bipolar transport nature. A comprehensive comparison is provided in terms of Schottky barrier height, DOS, and piezophototronic modulation.