SPLTRAK Abstract Submission
Fill Factor Loss in Perovskite Solar Cells Using Fullerene ETLs Caused by Air Exposure
Austin G Kuba, Alexander J Harding, Raphael Richardson, Ujjwal K Das, Kevin D Dobson, William N Shafarman
Institute of Energy Conversion, University of Delaware, Newark, DE, United States

The effect of air exposure on perovskite solar cells using fullerene electron transport layers (ETLs) was investigated. Coplanar conductivity measurements showed a loss of conductivity in C60 thin films, decreasing by 1 order of magnitude in 5 minutes, and 2 orders of magnitude in 35 minutes. N-i-p solar cells using C60 ETLs and MAPbI3 processed by 2-step close space vapor transport showed a progressive loss of FF and onset of s-shaped J-V curve over 15 minutes of air exposure. This effect was not observed for over 2 hours of air exposure for solar cells with SnO2 ETLs, indicating that the C60 is the source of the degradation. SCAPS1D was used to simulate perovskite solar cells with varying C60 ETL carrier concentration and mobility. A loss of FF and onset of s-shaped curve was predicted as the conductivity drops below 2x10-6 S/cm, in accordance with the experimental J-V curves. This work shows that air exposure to fullerene ETLs can cause rapid performance degradation in perovskite solar cells due to a corresponding increase in C60 resistivity.