Breaking the 11% Efficiency Barrier in Dye-Sensitized Solar Cells: Synergistic Co-Sensitization with CZ-1, TP-2, and Black Dye

This study introduces a synergistic co-sensitization strategy employing two novel organic dyes, CZ-1 (phenylcarbazole-based) and TP-2 (triphenylamine-based), alongside the well-established black dye, to enhance the performance of dye-sensitized solar cells (DSSCs). The novelty of the work lies in the strategic combination of these dyes to leverage their complementary absorption spectra and distinct electron-donating capabilities, extending light-harvesting capacity into the visible and near-infrared regions. Additionally, chenodeoxycholic acid (CDCA) was utilized as a co-adsorbent to mitigate dye aggregation, improve molecular distribution on the TiO2 surface, and suppress recombination losses. The co-sensitized DSSC featuring CZ-1, TP-2, and black dye achieved a record power conversion efficiency (PCE) of 11.67%, significantly surpassing the efficiency of systems sensitized with black dye alone (9.05%). The enhancement is attributed to the extended spectral absorption of the co-sensitized system, optimized dye orientation facilitated by CDCA, and improved charge transfer dynamics validated through electrochemical impedance spectroscopy (EIS). This study highlights the importance of molecular design and synergistic interactions in advancing DSSC technologies, offering a pathway for next-generation photovoltaic devices with improved efficiency and stability.