Effective control of the length of ZnO-TiO2 nanorod arrays as electron transport layer of perovskite solar cells with enhanced performance

摘要

Vertical ZnO nanorod arrays were synthesized by a polymer template method and modified by TiO2 shell via a sol-gel method. The core-shell structure of ZnO-TiO2 nanorod arrays was used as an electron transport layer (ETL) of perovskite solar cells (PSCs) and the length of the nanorod arrays was controlled by changing the hydrothermal growth time. The photovoltaic performance of the PSC prepared in ambient atmosphere was found to be crucially dependent on the length of ZnO-TiO2 nanorod arrays. ZnO-TiO2 nanorod arrays with a suitable length enabled complete infiltration of CH3NH3PbI3 perovskite into nanorod arrays and an increasement of carrier lifetime, eventually resulting in better cell performance. The PSC based on ZnO-TiO2 nanorod arrays with the length of 600 nm shows a power conversion efficiency of 10.24% under ambient air (RH similar to 40%, 25 degrees C), which is higher than the mean level of previous report. Meanwhile, the PCE of the unencapsulated device based on ZnO-TiO2 nanorod arrays retains 80% of the initial efficiency after 7 days in ambient atmosphere. This work provides the potential application of ZnO-TiO2 nanorod arrays with a suitable length as an effective ETL of efficient and stable all-solid-state PSCs.