High-efficiency solid-state quantum dot sensitized solar cells based on black TiO2 and an activated carbon electrode

Abstract

While quantum dot sensitized solar cells (QDSSCs) have been developed as one of the effective solutions to utilize solar energy, traditional QDSSCs with liquid electrolytes have the drawbacks of volatility and leakage, and solid-state QDSSCs are still limited by poor power conversion efficiency (PCE). In this study, black TiO₂ (denoted as R-P25 and L-P25) was prepared by modifying P25 TiO₂ through reduction and femtosecond laser engineering and used as the anode. CdSe/CdS quantum dots were employed for sensitization. A high-conductivity, solidified polysulfide electrolyte containing acrylamide (AM) was used, and a Ti mesh with an activated carbon (AC) layer served as the counter electrode (CE), constructing a solid-state QDSSC. The modified black TiO₂ with an amorphous shell–crystalline core structure exhibits excellent light absorption capabilities and abundant oxygen vacancies, significantly improving the photovoltaic efficiency of QDSSCs. In addition, AC can reduce the redox potential of polysulfide electrolytes, and the introduction of AM leads to the formation of a stable electrolyte structure in the solid state, resulting in stability and high ionic transport performance of the gel electrolyte. The synergistic effects of the superior photoelectric effect of black TiO₂ and low resistance of the gel electrolyte are responsible for the enhanced conversion efficiency and long-term stability of the QDSSCs, demonstrating a high PCE of 9.48%. Therefore, this work provides a new approach for the further development of QDSSCs.