A near-infrared thienyl-BODIPY co-sensitizer for high-efficiency dye-sensitized solar cells†
Two NIR BODIPY dyes T′2P2A and T′′2P2A were synthesized and used as photosensitizers in dye sensitized solar cells (DSSCs). T′2P2A and T′′2P2A were designed by incorporation of bis-thienyl vinyl and thienothiophene vinyl side-arms in the structure. This leads to a red shift in the absorption spectra leading to an enhancement in the incident photon to current conversion efficiency (IPCE). A high IPCE value of 64% at 750 nm and a power conversion efficiency (PCE) of 6.06% were observed for the T′2P2A based DSSC. Furthermore, based on the complementary absorption spectra of TP2A and T′2P2A, even more efficient co-sensitized DSSCs were fabricated. The DSSC based on TP2A + T′2P2A shows an enhancement in the IPCE from 47% to 74% at 550 nm compared to that based on the single dye system T′2P2A. Finally, a high PCE of 6.67% was obtained for the TP2A + T′2P2A co-sensitized DSSC, which was higher than the performances of each individual dye.