Multifunctional SnS Thin Film for Next‐Generation Room‐Temperature Gas Sensing and High‐Performance Photodetection

Tin sulfide (SnS) thin film has been extensively explored for gas sensing or photodetection individually; however its, simultaneous application as a multifunctional platform for both technologies remains rarely reported. For the first time, we demonstrate that using thermally evaporated SnS thin films can serve as a multifunctional platform, exhibiting high room‐temperature gas sensing alongside high‐performance photodetection. Structural and morphological analyses confirm the formation of phase‐pure orthorhombic SnS with nanoscale grains, uniform flake‐like morphology, and defect‐rich surfaces likely associated with tin vacancies. Optical studies reveal strong visible absorption coefficient with a direct bandgap of 1.94 eV, and moderate structural disorder (Urbach energy = 0.467 eV), supported by Raman and photoluminescence features associated with near‐band‐edge emission and defect states. Gas‐sensing experiments demonstrate excellent room‐temperature performance toward NO 2 and H 2 S in the concentration range of 5–20 ppm. The SnS sensor exhibits high sensitivities (186.2% for NO 2 and 182% for H 2 S at 20 ppm), detection limits in the sub‐ppm range (0.73 ppm for NO 2 and 0.24 ppm for H 2 S), and distinct response–recovery dynamics. Specifically, NO 2 detection is characterized by rapid response times with moderate recovery, whereas H 2 S exhibits slightly slower response but significantly prolonged recovery times. These characteristics confirm strong surface reactivity, efficient charge‐transfer processes, and gas‐dependent recovery kinetics. The Au/SnS/Glass photodetector displays rectifying I–V behavior, high photocurrent sensitivity (105%), large responsivity (17.69 A/W), excellent detectivity (1.73 × 10 11 Jones), and enhanced external quantum efficiency ( 4131%) . The transient photocurrent response exhibits fast, repeatable ON/OFF switching, with rise and decay times of   0.19 s and 0.17 s, respectively, consistent with defect‐assisted photoconductive gain. These results establish thermally evaporated SnS thin film as a low‐cost, environmentally benign, and multifunctional material platform for next‐generation room‐temperature gas sensors and high‐performance optoelectronic devices.