Zinc Oxide-Perylene Diimide Hybrid Electron Transport Layers for Air-Processed Inverted Organic Photovoltaic Devices

In this work, we report the formation of perylene diimide films, from green solvents, for use as electron transporting layers, when combined with ZnO, in inverted-type organic photovoltaics. A modified N-annulated PDI was functionalized with a tert-butyloxycarbonyl protecting group to solubilize the material, enabling solution processing from green solvents. Post-deposition treatment of films via thermal annealing cleaves the protecting group yielding the known PDIN-H material, rendering films solvent-resistant. The PDIN-H films were characterized by optical absorption spectroscopy, contact angle measurements, and atomic force microscopy. When used to modify the surface of ZnO in inverted-type organic photovoltaics (air-processed and tested) based on the PM6:Y6 and PTQ10:Y6 bulk-heterojunctions, the device power conversion efficiency increases from 9.8 to 11.0% and 7.2 to 9.8%, respectively.