Improved Photoelectrochemical Performances of Aqueous Mesoscopic Solar Cells

摘要

Conventional mesoscopic dye-sensitized solar cells using organic solvents based electrolytes generally have the disadvantages of high vapour pressure against reliable encapsulation, and most importantly, are not environmentally friendly. Aqueous electrolytes based on water possess advantages such as low-cost, earth-abundant, non-toxic and non-flammable, therefore, attracted considerable research interests. However, aqueous electrolyte would negatively shift the conduction band of TiO_2 as the water molecules irreversibly change the interfacial properties of the sensitized TiO_2 film. Tungsten doped (W-doped) TiO2 mesoporous nanoparticle aggregates, possessing high surface area and superior scattering effect, were used for photoanode preparation. The W-doping would induce a positive shift of the TiO_2 conduction band, and enhance the driving force for electron injection and collection efficiencies. The electrochemical impedance spectra indicated a retarded charge recombination and increased electron diffusion length after W-doping. Aqueous DSCs produced a significant improved the open circuit voltage of 712 mV and a short circuit current of 7.05 mA·cm~(-2), leading to an overall increased power conversion efficiency of 3.40% at 1 sun, a nearly 25% enhancement compared to the non-doped photoanode.