Low‐Temperature Deposition of Bi ₂ S ₃ via Solution‐based Combustion‐assisted Thin Film Deposition Technique for High Performance Self‐Powered Photoelectrochemical Photodetector

Abstract Recent breakthroughs in combustion‐assisted thin film deposition techniques have revolutionized the development of large‐area flexible electronics. These advancements enabled integration onto diverse substrates, offered significant cost‐effective manufacturing merits, and reduced environmental impact. This technique utilizes fuel and oxidizer‐ligands within the precursor to promote an exothermic reaction, enabling the low‐temperature thin film deposition of various conductive, semiconductive, and high permittivity dielectric metal oxides. However, there are nearly no reports on the low‐temperature deposition of metal sulfide thin film. In this study, leveraging the flexibility in precursor selection afforded by mist chemical vapor deposition, a solution‐based combustion‐assisted film deposition technique is employed to achieve the low‐temperature deposition of Bi ₂ S ₃ thin films. The Bi(NO ₃ ) ₃ and thiourea & hydrazine hydrate are applied as the oxidizer and fuel, respectively. The deposition mechanism is discussed from the temperatures and the concentration of additives (hydrazine hydrate and NaOH). The photoelectrochemical photodetectors fabricated using the solution‐processed Bi ₂ S ₃ thin films demonstrated interesting photodetection performance, exhibiting remarkable responsivity, rapid response speed, and high stability over 3600 s. This research would develop innovative approaches in low‐temperature deposition processes for metal sulfide thin films and unlock their full potential in next‐generation optoelectronic and energy conversion devices across multiple technological domains.