High-efficiency hole transport layer‑free perovskite solar cells utilizing TiO2, ZnO and bilayer TiO2/ZnO electron transport layers: A simulation approach

Abstract

Perovskite solar cells (PSCs) have attracted enormous interest due to their low cost and high-power conversion efficiency (PCE). This study demonstrates that removing the hole transport layer (HTL) from a PSC can simplify the device structure and reduce production cost, while still delivering reasonable efficiency. Three prototype HTL-free solar cells were simulated based on single TiO 2 , ZnO and double TiO 2 /ZnO electron transport layers (ETLs) to identify the configuration with the best performance for optimization. The FTO/ZnO/MAPbI 3 /Au architecture has been found more promising and has been further investigated using varied layer thickness, doping concentration, defect density, interface-defect density series and shunt resistance, and back contact work function. The optimal simulation parameters produced an optimized device with enhanced power conversion efficiency (PCE) of 34.55 %, fill factor of 90.74, short circuit current of 26.16 mA/cm 2 , and open circuit voltage of 1.46 V. The PCE of the optimized device decreased significantly with increasing temperature. The present device demonstrates superior photovoltaic characteristics compared to previous PSCs utilizing ZnO ETL.