Poly(vinylidenefluoride) polymers and copolymers as versatile hosts for luminescent solar concentrators: compositional tuning for enhanced performance

Novel host matrices based on fluoropolymers blended with poly(methyl methacrylate) (PMMA) are presented in this work for application in efficient and photochemically stable thin-film luminescent solar concentrators (LSCs). These systems consist of blends of PMMA with three different partially fluorinated polymers in different proportions: polyvinylidenefluoride homopolymer, a copolymer of vinylidenefluoride and chloro-trifluoro-ethylene, and a terpolymer of vinylidenefluoride, hexafluoropropylene and hydroxyl-ethyl acetate. A detailed chemical, physical and structural characterization of the obtained materials allowed us to shed light on the structure-property relationships underlying the response of such blends as a LSC component, revealing the effect of the degree of crystallinity of the polymers on their functional characteristics. An optimization study of the optical and photovoltaic (PV) performance of these fluoropolymer-based LSC systems was carried out by investigating the effect of blend chemical composition, luminophore concentration and film thickness on LSC device output. LSCs featuring copolymer/PMMA blends as the host matrix were found to outperform their homopolymer- and terpolymer-based blend counterparts, attaining efficiencies comparable to those of reference PMMA-based LSC/PV assemblies. All optimized LSC systems were subjected to weathering tests for over 1000 h of continuous light exposure to evaluate the effect of the host matrix system on LSC performance decline and to correlate chemical composition with photochemical durability. It was found that all fluoropolymer/PMMA-based LSCs outperformed reference PMMA-based LSCs in terms of long-term operational lifetime. This work provides the first demonstration of thermoplastic fluoropolymer/PMMA blends for application as host matrices in efficient and stable LSCs and widens the scope of high-performance thermoplastic materials for the PV field.