Performance enhancement of perovskite solar cells through interfacial engineering: Water-soluble fullerenol C60(OH)16 as interfacial modification layer

TiO2 is widely used in conventional n-i-p type perovskite solar cells (Pero-SCs) as electron transporting layer (ETL). However, its drawbacks such as photocatalytic properties, low electron mobility, and a process of high temperature sintering, hindered the further improvement of device performance. In this work, a vacuum-deposited fullerene C60 was utilized as ETL, and a easily accessible fullerene derivative, C60(OH)16 fullerenol, was employed between ITO electrode and C60 ETL to modify ITO for the first time. After introducing the C60(OH)16 fullerenol layer, the Pero-SC obtained the favorable energy level alignment between ITO cathode and perovskite layer, and the device based on C60(OH)16/C60 ETL achieved a champion PCE of 16.70%, which showed a 15.41% enhancement compared to the Pero-SC with pristine C60 ETL (14.47%). The mechanisms of performance improvement were systemically discussed with respect to the optimized energy level, efficient charge transport and reduced interfacial resistance. This work exhibited that fullerenol C60(OH)16 is a promising interfacial modification material for the n-i-p type Pero-SCs.