Synthesis and characterization of zinc carboxy–porphyrin complexes for dye sensitized solar cells

Abstract

Two zinc porphyrins, 2 and 8, have been synthesized. Porphyrin 8 displays better electronic communication between the dye and the TiO₂ electrode. Photophysical measurements and electrochemistry experiments suggest that both porphyrins are very promising sensitizers for dye-sensitized solar cells (DSSCs). It was found that their molecular orbital energy levels favor electron injection and dye regeneration in DSSCs. Solar cells sensitized by 2 and 8 were fabricated, and it was found that they show power conversion efficiencies (PCEs) of 5.27% and 7.13%, respectively. Photovoltaic measurements (J–V curves) together with the incident photon-to-electron conversion efficiency spectra of the two cells reveal that the higher PCE value of the DSSC based on 8 is ascribed to the higher short-circuit current (J_sc), open-circuit voltage (V_oc), and dye loading values. Moreover, the larger charge recombination resistance, longer electron lifetime and shorter electron transport time for 8 also confirm the higher value of the V_oc and the J_sc and the FF for the DSSC based on 8.