Wurtzite nanoparticle ink spray processing for chalcopyrite CuIn(S,Se)2 photovoltaic absorber layer

Abstract

CuIn(S,Se)2 solar cells have regained its significance mainly for its utilization in tandem cells for developing a low cost all solution processed tandem devices. However, achieving a dense, crack-free, and crystalline chalcopyrite- CuIn(S,Se)2 (ch-CISSe) through solution route is one of the key challenges in the fabrication of CISSe thin film solar cells (TFSCs). Here, we have utilized wurtzite-CuInS2 (wz-CIS) nanoparticle ink to obtain a chalcopyrite-CISSe absorber layer and demonstrated a 7.34 % efficient solar cell. Ink composition and spray parameters were optimised to produce compact crack-free films using nanoparticle-based inks. Further, selenization was performed to obtain chalcopyrite CuIn(S,Se)2 (ch-CISSe) and reduce the grain boundary density, which acts as recombination centres. The wz-CIS and ch-CISSe devices were fabricated by sequentially depositing the buffer layer (CdS), window layer (i-ZnO and Al–ZnO) and gold electrode. © 2023 Elsevier Ltd