Sn- and Pd-Free Synthesis of D–Π–A Organic Sensitizers for Dye-Sensitized Solar Cells by Cu-Catalyzed Direct Arylation

<A variety of D–π–A-type functional organic dyes are facilely synthesized by direct C−H arylation catalyzed by inexpensive copper salts. Under optimized reaction conditions, a broad substrate scope with good functional group compatibility was demonstrated. Based on this synthetic strategy, three new dye sensitizers (CYL-5–7) were designed and fabricated for use in dye-sensitized solar cells (DSSCs). Photovoltaic characterization showed that these devices gave open-circuit voltages of 0.65–0.75 V, short-circuit currents of 5.90–12.60 mA cm⁻², and fill factors of 65.6–76.9 %, corresponding to power conversion efficiencies (PCEs) of 2.95–6.20 %. This work represents the first use of Cu-catalyzed C−H arylation for a step-saving, Sn-free synthesis of precursor dyes for DSSC applications.