Boosting the Efficiency of CZTS/Si Tandem Solar Cells Using In2O3 Layer in CZTS Top Cell

Abstract

AbstractWhile single‐junction solar cells may be capable of attaining AM1.5 theoretical efficiency of 33.16%, infinite multijunction (MJ, Tandem) solar cells will have a limiting efficiency of 86.8%. Tandem solar cells based on crystalline silicon (c‐Si) bottom cells are therefore attracting great interest. An interesting candidate for the top cell absorber is represented by copper zinc tin sulfide Cu2ZnSnS4 (CZTS). In this work, the CZTS/Si tandem solar cell is optimized by using indium oxide / Cadmium sulfide (In2O3/CdS) hybrid buffer. This present work reports CZTS/Si solar cell with an open‐circuit voltage VOC of over 0.942 V and a JSC of 34.7 mA cm−² by adding In2O3 layer in the CZTS top cell. The added In2O3 layer has a thickness of 0.022 µm and is n‐doped with a concentration of 1e20 cm−3. Compared with a CZTS/Si in which the hybrid buffer is of CdS, the efficiency is increased from 13.5% to 28.4%. These hybrid In2O3/CdS buffers provide a promising way to reduce the VOC deficit and further boost the efficiency of CZTS/Si solar cells.