Concordantly fabricated heterojunction ZnO–TiO2 nanocomposite electrodes via a co-precipitation method for efficient stable quasi-solid-state dye-sensitized solar cells

Abstract

This manuscript is concerned with the successful attempts we have made to fabricate nanostructured spheres composed of mixed metal oxides. ZnO/TiO₂ nanocomposites supported on an FTO substrate are used as the photoanode electrode for quasi-solid-state dye-sensitized solar cells (QS-DSSCs). The phase purity of the ZnO and TiO₂ phases of the composite shell has been studied by X-ray diffraction peak analysis. A novel gel polymer electrolyte based on a poly(acrylamide)–poly(ethylene glycol) composite and a binary organic solvent was prepared. The polymer gel electrolyte based on the composite of poly(acrylamide)–poly(ethylene glycol), the binary organic solvent of ethylene carbonate and propylene carbonate and the additive of 4-tert-butylpyridine has been employed to fabricate a quasi-solid-state dye-sensitized solar cell. The conversion efficiency of the dye-sensitized solar cells with nanocomposites is 6.5% which is more than double compared with that of bare ZnO nanoparticle photoanodes (3.8%). We believe that this improvement comes from the synergetic effect between ZnO and TiO₂, which increases dye absorption, electron transport and electron lifetime, as discussed with the EIS and loaded absorption results. From the current–voltage and incident photon-to-current conversion efficiency (IPCE) measurement, the conductivity of the nanocomposite ZnO–TiO₂ was shown to be higher compared to the nanostructured ZnO itself. This simple method can be universally adopted for all quasi-solid-state electrolyte-based DSSCs in order to improve their performance and durability.