Abstract

The pursuit of high-efficiency and economically viable photovoltaic (PV) technologies continues to drive interest in functional semiconductors with tunable optoelectronic characteristics. Chalcopyrite and chalcogenide materials-such as CuIn_1-xGa_xSe₂, CuₓS, ZnTe, Sb₂Se₃ and Cu₃SnS₄-are particularly promising due to their adjustable direct bandgaps, high absorption coefficients, and compatibility with thin-film device architectures. Controlled thermal processing of these films leads to distinct phase transformations, with XRD, Raman, SEM, and EDAX analyses revealing improved crystallinity, enlarged crystallite dimensions, and enhanced compositional uniformity at elevated annealing temperatures. These structural improvements translate into modified band gaps, reduced defect-related absorption, and more favourable refractive index profiles, demonstrating their suitability as absorber layers. Electrical measurements confirm p-type conductivity, with mobility, resistivity, and carrier concentration systematically influenced by thermal treatments. Schottky barrier and pn-heterojunction devices fabricated from these films exhibit clear rectification, well-defined barrier formation, and measurable photoresponse under illumination. Complementary chalcogenide and oxide nanoparticle thin films, including CdS, β-In₂S₃, ZnSe, and ZnO, act as effective n-type window or buffer layers owing to their wide band gaps and efficient electron transport behaviour. Annealing-driven nanoparticle evolution enables precise control over crystallite size, bandgap, conductivity, and surface morphology, further optimising their functionality in heterojunction solar cells. This presentation highlights recent progress in the synthesis, structural tailoring, optical modulation, and charge-transport engineering of chalcopyrite and chalcogenide thin films grown using sequentially evaporated layered deposition (SELD) and thermally evaporated nanoparticle precursors prepared by direct fusion. Emphasis is placed on the role of post-deposition annealing in enhancing device-relevant properties. Collectively, these advancements demonstrate the strong potential of these nanostructured layers for realising scalable, efficient, and cost-effective thin-film photovoltaic technologies.

Biography

Prof. Naresh Padha is a Professor of Physics at the University of Jammu, India, with over 36 years of teaching, research, and academic administrative experience. He obtained his PhD in Physics from the University of Jammu in 1993. His research interests include compound semiconductor thin films, chalcogenide materials, Schottky diodes, and photovoltaic and optoelectronic devices. He has supervised 14 PhD theses, 22 M.Phil dissertations completed several major research projects funded by UGC, DST, DRDO, and RUSA, and has published more than 87 research papers in reputed international journals.