Thin-Film Photovoltaics Using Cu(In,Ga)Se₂Nanomaterials

 Cu(In,Ga)Se2 (CIGS) is a promising absorber material for thin film solar cells because of its excellent thermo-chemical stability and high power conversion efficiency. Despite the excellent performance, commercialization of CIGS solar cell technology has been hindered due to issues related to the preparation of the absorber layer. The manufacturing of CIGS absorbers needs innovative technological development to make them commercially competitive, simplified and cost-effective. In this connection, the solution process utilizing CIGS nanomaterial precursor is a non-vacuum, low-cost, non-toxic and scalable approach with a high potential for developing an absorber layer. The typical processes comprise the synthesis of high-quality CIGS nanomaterials followed by printing constituent precursors in thin film form. Subsequently, thermal/photonic post-treatments of the printed precursors transform into a high-quality photovoltaic-grade absorber. The chapter critically reviews CIGS nanomaterial synthesis methods and discusses various printing techniques. The discussion follows an investigation of printed thin film's thermal and photonic processing to realize a high-quality CIGS absorber layer suitable for thin film photovoltaics. The processing parameters such as annealing profile, post-treatment, annealing atmosphere, Selenium source, photonic fluences, and alkali doping are discussed to understand their impact on the absorber's composition, morphology, and optoelectronic properties. The findings and related reviews afford critical insight into the absorber thin film design to improve the performance of solution-processed chalcopyrite solar cells. Finally, current challenges and prospects for effective technology implementation are discussed.

Keywords: Alkali doping, CIGS, Intense pulsed light, Laser annealing, Nanomaterial, Photonic sintering, Selenization, Solar cells, Thin films.