Solution Processed Pure Sulfide CZCTS Solar Cells with Efficiency 10.8% using Ultra‐Thin CuO Intermediate Layer

In this work, we demonstrate that incorporating an ultra‐thin p‐type cupric oxide (CuO) enhances performance and stability of the solution processed Cu2(Zn0.6Cd0.4)SnS4 (CZCTS)/CdS thin film solar cells. In sol‐gel CZCTS/CdS thin film solar cells, nanoscale CuO films (4 – 32 nm) were deposited on top of molybdenum (Mo) by magnetron sputtering and this was used as an intermediate layer (IL). The CuO IL thickness has a significant effect on the short‐circuit current density (JSC) in CZCTS/CdS solar cell devices. As a result, a maximum power conversion efficiency (PCE) of 10.77% has been measured for the optimized device with 4 nm CuO compared with 10.03% for the reference device without CuO layer. Furthermore, stability of the devices is enhanced significantly by incorporating CuO IL. The present work demonstrates that through proper design of the CuO intermediate layer thickness, both back interface quality and optical property of the CZCTS absorber can be tuned to enhance the device performance.