8.0% Efficient Submicron CuIn(S,Se)2 Solar Cells on Sn:In2O3 Back Contact via a Facile Solution Process

High-performance chalcopyrite solar cells have been fabricated on transparent conductive oxide (TCO) back contact through an environmentally benign solution, showing great potential for bifacial application. Ultrathin (around 550 nm) CuIn(S,Se)2 (CISSe) solar cells were successfully deposited on Sn:In2O3 (ITO) back contact via spin-coating of metal-chloride N,N- dimethylformamide (DMF) solution, followed by selenization. The ultrathin devices achieved a conversion efficiency of 7.5% when the precursor film was selenized at 520 degrees C. With the increase in the absorber thickness to submicron (740 nm), the solar cells exhibited not only a higher short-circuit current density but also an improved fill factor compared to the ultrathin devices, which resulted in an efficiency enhancement to 7.9%. Furthermore, NaCl solution preselenization treatment was demonstrated to improve the performance of CISSe solar cells. When the submicron absorber was subject to 1 M NaCl solution prior to selenization, an 8.0% efficient CISSe device was achieved. To the best of our knowledge, this is the topmost performance for submicron CISSe solar cells fabricated from solution-based precursors on TCO back contact.

Automated summary

High-performance chalcopyrite solar cells have been fabricated using an environmentally friendly solution, showing great potential for bifacial application. The efficiency of the solar cells can be improved by adjusting the absorber thickness and using a NaCl solution preselenization treatment.