Detailed Insight into the CZTS/CdS Interface Modification in the Monograin Layer Solar Cells

Abstract: Kesterite absorber material Cu2ZnSnS4 (CZTS) is attractive candidate for abundant, non-toxic and high efficiency solar cells. Kesterite based unique monograin layer solar cell technology was developed by the Tallinn University of Technology researchers more than a decade ago targeting building integrated applications as light-weight, semitransparent and flexible photovoltaic modules. The power conversion efficiency of CZTS solar cells is still limited by deep defects, low minority carrier lifetime and high recombination rates at the CZTS/CdS interface. Hereby, we present recent advancements in the development of kesterite monograin layer solar cells, with the focus on p-n junction modifications. Firstly, we focused on the post-annealing of CZTS/CdS interface, which have shown the potential for the high‐performance device. Detailed analysis of air-annealing effect of CZTS/CdS on the interface properties and on the performance of CZTS monograin layer solar cells will be presented. Secondly, an effective method to reduce further interface recombination of CZTS monograin layer solar cells is the Cd diffusion into surface of CZTS and replacement of CdS:Cu after annealing process by fresh CdS buffer layer. As a result, we obtained CZTS monograin layer solar cells with 11.5% power conversion efficiency with significantly reduced series resistance. Detailed analysis of temperature dependent J-V characteristics of the modified CZTS monograin layer solar cell will be presented in the workshop. This research has been partially supported by the CUSTOM-ART Project, funded from the European Union’s Horizon 2020 Research and Innovation Programme under the grant agreement No 952982.Invited talk at the 4th Asia-Pacific Kesterite Workshop at the 31st PVSEC in Sydney 2021