Photocurable polymeric coatings for improved stability and multifunctionality in solution-processable photovoltaics

Photovoltaic (PV) technology has evolved rapidly in the past few decades and now encompasses a large variety of materials and device structures. A key aspect to be taken into account in any PV technology is the operational durability of these systems in outdoor conditions. Clearly, loss of performance during operation represents a significant drawback and limitation for their commercialization. In this context, the large compositional flexibility of polymeric materials as well as their proven easy processability may be of great help in imparting improved durability to PV systems. In this contribution, a series of photocurable fluoropolymeric systems will be presented that find application as multifunctional coatings for different solution-processable PV devices, including dye-sensitized solar cells (DSSCs), organic PVs (OPVs) and perovskite solar cells (PSCs). Aspects related to the chemical functionalization of the coating precursors will be addressed in view of the incorporation of multiple functionalities into the final coating material, such as high photochemical durability, luminescent down-shifting, UV-screening, high hydrophobicity and easy-cleanability. In addition, a thorough chemical and physical characterization of the coating materials will be presented. The functional properties of these systems will be evaluated by integrating them into operating DSSC, OPV and PSC devices. It will be demonstrated that by synthetically tuning the functionality of the coating system as a function of the target PV technology, improved power conversion efficiency and unmatched long-term operational stability can be achieved on all PV systems investigated. The general approach presented here gives a clear demonstration of the enormous potential of this technology for the straightforward fabrication of solution-processable PV devices with improved performance and enhanced stability without altering the chemistry of the photoactive layer.