Recent Advances in Transition Metal Doped PbS Thin Films Prepared by Chemical Deposition Methods: A Comprehensive Review

Lead sulphide (PbS) thin films doped with metals have attracted significant attention for use in next-generation photovoltaic and optoelectronic devices. This interest primarily arises from their tuneable bandgap, strong optical absorption, and quantum confinement effects associated with reduced crystallite size. This review presents recent developments in the synthesis and characterization of transition-metal doped PbS thin films prepared using solution-based methods. The review focuses on the influence of key deposition parameters, including precursor concentration, choice of complexing agent, bath temperature, solution pH, and dopant concentration on the structural, optical, morphological, and electrical properties of PbS thin films. The reports have shown that metal doping can significantly modify crystallite size, optical bandgap, carrier mobility, and surface morphology, thereby influencing the suitability of these films for solar cell absorber applications. However, several challenges still need to be addressed, including achieving uniform dopant distribution, preventing secondary phase formation, reducing defect density, and improving long-term stability. By bringing together recent findings, this review highlights the major material related factors that limit device performance and discusses possible processing strategies for developing more stable and efficient solution processed PbS based photovoltaic absorber layers.