Efficient Nanorod Arrays Perovskite Solar Cells: A Suitable Structure for High Strontium-Substitution in a Nature Environment

摘要： Organic-inorganic hybrid perovskite solar cells (PSCs) have become a research hotspot because of their excellent power conversion efficiency (PCE), but the presence of toxic lead (Pb) in perovskite film has significantly limited their commercial application. In this study, using a TiO2 nanorod arrays (TNRAs) as the electron transport layer (ETL), strontium chloride (SrCl2) was chosen to fabricate lead-less PSCs in air environment (relative humidity, RH=50%) by a simple two-step spin-coating method. The influence of introduced strontium (Sr) on the perovskite films and cell properties was systematically investigated by various characterization methods. With increasing Sr substitution amount from 0 to 15 mol%, the formed perovskite films with a compact structure and a large crystalline size essentially remained invariable, while residual PbI2 was reduced, which is beneficial for the cell performance. The optimal PCE of 16.08% (average PCE = 15.37%) was obtained for the 5 mol% Sr-substituted PSCs because of the enhanced charge extraction from the perovskite film to the TNRAs and the suppressed charge recombination in the PSC. Both the humidity and thermal stability of the Sr-substituted PSCs were improved. More importantly, the 15 mol% Sr-substituted PSCs still exhibited a PCE of 15.09% in air (RH = 50%), maintaining 99% of the cell efficiency of the pristine (0 mol% Sr) PSC (15.27%), suggesting that the TNRAs structure is suitable for synthesis of high Sr-substituted lead-less PSCs.