Core–shell ZnO@TiO2 hexagonal prism heterogeneous structures as photoanodes for boosting the efficiency of quantum dot sensitized solar cells

Abstract

In quantum dot sensitized solar cells (QDSSCs), the photoanode provides a stable support for the quantum dots, and promotes the production of photogenerated electrons and the transfer to external circuit. Therefore, it is very important to search for excellent photoanodes for the commercial application of QDSSCs. In this paper, a core–shell ZnO@TiO₂ hexagonal prism heterogeneous structure was prepared by a two-step hydrothermal method. The ZnO@TiO₂ heterogeneous structure not only has a unique 1D hexagonal prism morphology, but also can effectively inhibit the electron–hole recombination and has a greater light response and higher collection efficiency while speeding up the electron transmission rate. By adjusting the concentration of the TiO₂ source, the best photoanode material Zn@Ti-2 was explored, and it showed excellent cell performance: J_sc = 25.4 mA cm⁻², V_oc = 0.71 V, PCE = 8.5%, and FF = 0.49. Compared with a single ZnO photoanode, the PCE value is increased by 25%. EIS, Tafel polarization and transient photocurrent responses confirm that the Zn@Ti-2 photoanode has higher catalytic activity and stability. Therefore, Zn@Ti-2 may be a promising photoanode material for QDSSCs.