Numerical simulation analysis of effect of energy band alignment and functional layer thickness on the performance for perovskite solar cells with Cd1-xZnxS electron transport layer

Abstract

Energy band alignment between perovskite layer and charge transport layers is critical to the perovskite solar cell efficiency. The thickness of functional layers also has a great influence on the device performance. We have optimized the energy band alignment at the interface between electron transport layer (ETL) and perovskite layer by using appropriate Cd1-xZnxS ETL (x represents the Zn molar concentration). Different hole transport layers (HTLs) have also been selected to address the mismatching energy band alignment at perovskite/HTL interface. Additionally, the thickness of Cd1-xZnxS ETL and perovskite layer (MAPbI3) has been optimized. We performed all the analysis via numerical simulation with wx Analysis of Microelectronic and Photonic Structures (wxAMPS) software. We also compared the results obtained in this study, with results reported in other literature to ascertain the validity of the results. The results show that the device performance could be improved by appropriately increasing the molar concentration of Zn in Cd1-xZnxS. Spike-type energy band structure at the interface of MAPbI3/HTL could favor the performance of perovskite solar cells when MASnBr3 is adopted as HTL. Appropriate ETL and perovskite layer thickness would increase the short circuit current and reduce the recombination loss.