Luminescent Downshifting by Photo‐Induced Sol‐Gel Hybrid Coatings: Accessing Multifunctionality on Flexible Organic Photovoltaics via Ambient Temperature Material Processing

Abstract

A novel high‐durability multifunctional organic–inorganic hybrid coating material is presented in this work as luminescent down‐shifting (LDS) host matrix system for flexible organic photovoltaic (OPV) devices. Such new LDS coating is obtained by incorporating a convenient fluorescent organic dye in an appropriately functionalized fluoropolymeric resin that can be readily crosslinked by means of a dual‐cure mechanism with a single‐step ambient‐temperature photo‐induced sol–gel process. Due to its peculiar characteristics, the newly proposed system may be readily implemented in heat‐sensitive flexible devices. By carefully tuning the amount of organic fluorophore in the hybrid coating material, a maximum increase in power conversion efficiency exceeding 4% is achieved on devices incorporating the new LDS layer with respect to control systems. This represents the highest efficiency enhancement reported to date on flexible OPVs by means of a polymer‐based LDS layer. In addition, long‐term accelerated weathering tests (>550 h) highlight the excellent stability of LDS‐coated OPV devices, which can retain 80% of their initial performance, as opposed to the dramatic efficiency decay experienced by control uncoated devices. The approach presented here opens the way to the straightforward incorporation of versatile multifunctional light‐managing layers on flexible OPV systems for improved device efficiency and lifetime.