Bending-stability Interfacial Layer as Dual Electron Transport Layer for Flexible Organic Photovoltaics

The flexibility of organic photovoltaics (OPVs) has attracted worldwide attention in recent years. To realize the bending-stability of OPVs, it is necessary to put forward the bending-stability of interfacial layer. A novel bendable composite is explored and successfully applied as an electron transport layer (ETL) for fully-flexible OPVs. We incorporated poly(vinylpyrrolidone)(PVP) into conjugated electrolytes (CPE) to composite a bendable ETL for high-performance OPVs devices. Fortunately, the devices based on PVP-modified CPE exhibited better device performances and more excellent mechanical properties of bendability. The fullerene-free OPVs based on PM6:IT-4F with CPE@PVP as ETLs yield the best power conversion efficiency (PCE) of 13.42%. Moreover, a satisfying efficiency of 12.59% has been obtained for the fully-flexible OPVs. As far as we know, this is one of the highest PCE for fully-flexible OPV based PM6:IT-4F system. More importantly, the flexible OPVs devices can retain more than 80% of its initial efficiency after 5000 bending cycles. Furthermore, among various curvature radii, the mechanical properties of the device based on CPE@PVP are superior to those of the device based on bare CPE as ETL. These findings indicate that the functional flexibility of CPE as a cathode interfacial layer is an effective strategy to fabricate high-performance flexible devices in the near future.

Automated summary

This study explores a novel bendable composite, successfully applied as an electron transport layer for fully-flexible OPVs, showing better device performances and mechanical properties.