Solution processed CZTSSe thin film solar cell absorber: Ink formulation and characterization

High power conversion efficiency, cost-effective materials and scalable manufacturing process are the main pillars of large-scale production of photovoltaic (PV) solar cells. In this study, we present a scalable manufacturing process of Cu2ZnSn(S,Se)4(CZTSSe) thin films by formulating stable ink from cost-effective metal salt precursors using non-toxic solvent. Precursor thin films are deposited by spin coating followed by baking on a pre-heated hot plate at 250 °C for 2 min to remove the residual solvent and finally crystallized at high temperature annealing under Se containing environment. The XRD pattern shows well-resolved characteristic peaks of CZTSSe phase while SEM images show highly dense layer with some voids at the back contact. Further optimization and fabrication of device for solar cell application is under study. Our non-hazardous functional ink formulation solvent system and absorber fabrication strategies offer insights for rational design of variety of PV materials and devices for high power conversion efficiency solar cells.