This study explores the synthesis of strontium-doped bismuth sulfide ( \({{\text{Bi}}}_{2} {\text{S}}_{3} :{\text{Sr}}\) ) thin films using the Nebulizer Spray Pyrolysis (NSP) technique, focusing on their photodetector properties. Comprehensive analyses of the structural, morphological, optical, and electrical characteristics were conducted to elucidate the behaviour of the materials. The crystallite size was found to be vary in the range of 19 –23 nm with Sr-doping contents. The optical study shows that the band gap for pure \({\text{Bi}}_{{2}} {\text{S}}_{{3}}\) is approximately \(2.59\;eV\) and decreases with Sr doping to \(2.28 eV\) . PL study revealed photo-responsive emission bands at wavelengths of approximately 420 nm (2.95 eV), 454 nm (2.73 eV), 483 nm (2.56 eV), and 524 nm (2.36 eV) after excitation with a 350 nm laser source. Electrical measurements indicated that 2% Sr doping in Bi₂S₃ significantly enhanced the photocurrent, with a responsivity of 6.16 × 10⁻1 A/W, detectivity of 3.10 × 1011 Jones, and an external quantum efficiency (EQE) of 199%. These improvements suggest that 2% Sr-doped \({\text{Bi}}_{{2}} {\text{S}}_{{3}}\) thin films are promising candidates for photodetector applications.
