CuInGaSe2 Thin-Film Electrodeposition Developments: A Comprehensive Review

Due to their remarkable long-term stability, variable bandgap, and relatively high absorption coefficient, copper indium gallium diselenide (CIGS) solar devices are among the most promising photovoltaic technologies due to their compatibility with lightweight substrates and special applications. This review critically discusses recent progress in the electrodeposition-based fabrication of CISe/CIGSe absorber layers, with special focus on electrolyte chemistry, electrochemical deposition mechanisms, precursor composition and morphology, post-deposition selenization/sulfurization, absorber quality, and photovoltaic device performance. We discuss aqueous and non-aqueous electrolytes, one-step and sequential electrodeposition, pulse-based deposition techniques, compositional control, film quality enhancement, Cd-free buffer layers, and large-area processing. The issues arising from the varied electrochemical behaviors of Cu, In, Ga, and Se are discussed, with specific emphasis on hydrogen evolution, limited integration of Ga, development of secondary phases, inhomogeneity of precursors, and process reproducibility. We review recent progress in device performance and explain typical manufacturing methods, and we summarise the key criteria for scaled electrodeposition. This review therefore sets up an integrated processing–structure–performance perspective for the further development of efficient and industrially relevant electrodeposited CIGSe solar cells.