Cu2ZnSn(S,Se)4 from annealing of compound co-sputtered precursors – Recent results and open questions.

Highlights • Recent work on CZTS solar cells from compound sputtered precursors is reviewed. • Studies of back contacts for CZTS should include influence on Na transport and re-optimization of the annealing process. • Variation in composition and chalcogen pressure during annealing can point to what defects are limiting performance. • For sulfide CZTS, CdS buffer layer must be replaced with a material with higher conduction band minima. Abstract Cu 2 ZnSn(S,Se) 4 (CZTS) thin film solar cells have reached efficiencies of up to 12.6% and current research is focused on understanding reasons for device limitations. At Uppsala University, a CZTS synthesis route based on compound sputtering and annealing in elemental vapors is used. Variation of chemical composition and annealing conditions is used as a tool to try to understand defect-related material- and device properties. Front and back contacts are also studied with focus on energy band matching at the hetero-interface using atomic layer deposition buffer layers and chemical stability of the back contact. In this review, we discuss recent work from our group, with reference to related work in the literature and with regards to areas for future work. [ABSTRACT FROM AUTHOR]