ИСТИНА

Perovskite solar cells (PSCs) have gained much attention because of their impressive power conversion efficiency (PCE) exceeding 25%. Among all types of PSCs, planar structure devices with an n-i-p configuration have attracted increasing interest because of their simple structure and easy fabrication. To achieve high performance characteristics of these devices, the choice of electron-transport layer (ETL) is important. Currently, low-temperature-processed SnO2 thin films are widely used as ETLs to fabricate efficient and stable planar PSCs. The most widely used passivation coatings are based on the fullerene derivative [6,6]-phenyl-C61-butyric acid (PCBA) with carboxylic acid functional group. We have synthesized five fullerene derivatives bearing different types and different numbers of addends, which are also able to passivate SnO2 layer. Further, we have investigated them in n-i-p type devices to reveal the correlation between the molecular formula and the performance of PSCs. Optimized passivation interlayers of monocyclopropanated fullerene derivative with carboxylic group improved the efficiency of perovskite solar cells as compared to conventional PCBA from 17.0% to 19.5%. This study highlights the key role of molecular design in passivation of SnO2 for pursuing high performance PSCs with n-i-p configuration.