Electrodeposited mesoporous TiO2 thin films and their application as the scalable electron transport layer for perovskite solar modules

In this study, we present the utilization of electrodeposited TiO2 mesoporous film (ED-MS-TiO2) as the electron transport layer (ETL) for perovskite solar cells, especially marking the first report of its application in perovskite solar modules. In the first part of this paper, we refine the electrodeposition process to enhance the porosity of the ED-MS-TiO2 thin film by elevating the ED temperature from room temperature to a mild 60 degrees C. Notably, the ED-MS-TiO2 ETL fabricated at 60 degrees C demonstrates comparable charge extraction capability and conversion efficiency to the benchmark ETL produced via the widely adopted spin-coating technique, achieving a remarkable 20.5 %. Furthermore, we demonstrate the immense superiority of the ED process in achieving uniformity in the preparation of large-area ETLs. Our current findings reveal that ED-MS-TiO2 exhibits exceptional uniformity control, with a thickness distribution of 122.69 +/- 8.39 nm on a 100 cm2 substrate, while its spin-coated counterpart exhibits poor thickness control, measuring 135.72 +/- 50.72 nm. Moreover, perovskite solar modules (5 cm x 5 cm) employing the optimized ED-MS-TiO2 ETL attain an impressive efficiency of 15.63 %, surpassing counterparts utilizing spin-coated TiO2 ETLs, which achieve only 9.70 %.