Preparation of Zr-doped mesoporous TiO2 particles and their applications in the novel working electrode of a dye-sensitized solar cell

Abstract

This paper presents an implementation of our recent theory on the suspension of electron-hole recombination via electronic- and micro-structure optimization to study the influence of Zr-doping on the efficiency (η) of TiO2-based dye-sensitized solar cells (DSSCs). We developed a four-layered working electrode, in which the size of particles increased from the bottom layer of TiO2 (P-25) through three successive layers of Zr-doped TiO2, which were calcined at 450, 600, and 850°C respectively. The enhancement in open-circuit photovoltage (Voc) and short-circuit photocurrent density (Jsc) can be attributed to the electronic- and micro-structures in the working electrode. The former is related to band bending, whereas the latter is related to light-scattering within multiple layers. Simulation results (FactSage) demonstrate that Zr doping in TiO2 can suspend or delay the formation of oxygen vacancies and thereby reduce the number of electron scattering centers, which helps to suspend electron-hole recombination by strengthening Ti-O bonds. The proposed four-layered working electrode produced an 80.2% increase in η, compared with DSSCs using a TiO2 (P-25) electrode. This study demonstrated a novel metal doping strategy for the manipulation of electronic structure and photoelectron conversion efficiency. The proposed methodology could also be used to guide the design of photo-catalysts in general.