Attributes of High-Performance Electron Transport Layers for Perovskite Solar Cells on Flexible PET versus on Glass
Marwa Dkhili, Giulia Lucarelli, Francesca De Rossi, Babak Taheri, Khadija Hammedi, Hatem Ezzaouia, Francesca Brunetti, Thomas M. Brown
Abstract
was 76% lower in relative terms, on average, than those on PET, indicating considerably better blocking behavior of ETLs on glass, which to a large extent explains the differences in average PCE (+29% in relative terms for glass vs PET) between these two types of devices. Importantly, we also found a clear trend for all ETLs and for different substrates between the wetting behavior of each surface and the final performance of the device, with efficiencies increasing with lower contact angles (ranging between ∼50 and 80°). Better wetting, with average contact angles being lower by 25% on glass versus PET, was conducive to delivering higher-quality layers and interfaces. This cognizance can help further optimize flexible devices and close the efficiency gap that still exists with their glass counterparts.