Vitamin C for Photo-Stable Non-fullerene-acceptor-Based Organic Solar Cells

The recent advent of the new class of organic molecules,the so-callednon-fullerene acceptors, has resulted in skyrocketing power conversionefficiencies of organic solar cells. However, rapid degradation occursunder illumination, particularly when photocatalytic metal oxide electrontransport layers are used in these devices. We introduced vitaminC (ascorbic acid) into the organic solar cells as a photostabilizerand systematically studied its photostabilizing effect on invertedPBDB-T:IT-4F devices. The presence of vitamin C as an antioxidantlayer between the ZnO electron transport layer and the photoactivelayer strongly suppressed the photocatalytic effect of ZnO that inducesNFA photodegradation. Upon 96 h of exposure to AM 1.5G 1 Sun irradiation,the reference devices lost 64% of their initial efficiency, whilethose containing vitamin C lost only 38%. The UV-visible absorption,impedance spectroscopy, and light-dependent voltage and current measurementsreveal that vitamin C reduces the photobleaching of NFA moleculesand suppresses the charge recombination. This simple approach usinga low-cost, naturally occurring antioxidant, provides an efficientstrategy for improving photostability of organic semiconductor-baseddevices.

Automated summary

The introduction of vitamin C into organic solar cells as a photostabilizer successfully suppresses the photocatalytic effect of ZnO and improves the photostability of the devices. After 96 hours of exposure to solar irradiation, devices with vitamin C only lost 38% of their initial efficiency compared to 64% in reference devices. The presence of vitamin C reduces the photobleaching of NFA molecules and inhibits charge recombination.