Controlled synthesis of monodispersed ZnO nanospindle decorated TiO2 mesospheres for enhanced charge transport in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have undergone extensive research and development to improve the device performance for commercial applications and for indoor applications in particular. Currently, titanium dioxide (TiO2) is a key photoanode candidate for DSSC device assemblies. However, the high recombination rate at the interface and low electron mobility of TiO2 remain very challenging disadvantages in devices using stand-alone TiO2 structures as the photoanode. Herein, we report a new scheme consisting of ZnO nanospindles decorated on TiO2 mesospheres as a long-term stable photoanode and explore the photon-induced charge carrier migration/transfer kinetics. Different proportions of ZnO spindles (0.05%, 0.10%, 0.15%, 0.20%, and 0.25%) decorated on the mesosphere TiO2 were effectively synthesised using a simple solvothermal method and the resulting composites were explored as photoanodes in DSSCs. DSSC devices composed of TiO2/ZnO nanocomposites demonstrated improved photovoltaic characteristics at different temperatures as well as exhibiting long-term durability. Regarding photovoltaic performance, the DSSC device with the TZC-0.05 photoanode offered an excellent power conversion efficiency (PCE) of 5.26% and an open circuit voltage V-OC of (0.75 V). Furthermore, a long-term stability test of the TZC-0.05 based DSSC device exhibited only a slight drop in the PCE as well as showing stable V-OC and FF performance. The best performing DSSC device (TZC-0.05) was studied at various temperatures from 30 to 55 degrees C, and the best response was exhibited at 35 degrees C, which is nearly equal to room temperature conditions.

Automated summary

In this study, a new scheme consisting of ZnO nanospindles decorated on TiO2 mesospheres as a stable photoanode was reported, and the kinetics of photon-induced charge carrier migration/transfer were explored. Different proportions of ZnO spindles decorated on mesosphere TiO2 were synthesized and used as photoanodes in DSSCs. The DSSC device with the TZC-0.05 photoanode showed excellent photovoltaic performance and long-term stability, with the best response exhibited at 35 degrees Celsius.