Nanocrystalline Titanium Oxide Electrodes for Photovoltaic Applications

TLDR

The study demonstrates how TiO₂ electrode microstructure, governed by precursor chemistry, hydrothermal growth temperature, binder addition, and sintering, affects photovoltaic performance. Photovoltaic action is achieved by a ruthenium dye monolayer on TiO₂ that, upon photon excitation, injects electrons into the semiconductor, which are extracted by the internal electric field while the dye’s positive charge is transferred to a redox mediator, with film porosity and light scattering tuned by processing parameters. The resulting photoelectrochemical cell reaches a 10 % power conversion efficiency using mesoporous, nanostructured anatase TiO₂ films.

Abstract

During the past five years, we have developed in our laboratory a new type of solar cell that is based on a photoelectrochemical process. The light absorption is performed by a monolayer of dye (i.e., a Ruthenium complex) that is adsorbed chemically at the surface of a semiconductor (i.e., titanium oxide (TiO 2 )). When excited by a photon, the dye has the ability to transfer an electron to the semiconductor. The electric field that is inside the material allows extraction of the electron, and the positive charge is transferred from the dye to a redox mediator that is present in solution. A respectable photovoltaic efficiency (i.e., 10%) is obtained by the use of mesoporous, nanostructured films of anatase particles. We will show how the TiO 2 electrode microstructure influences the photovoltaic response of the cell. More specifically, we will focus on how processing parameters such as precursor chemistry, temperature for hydrothermal growth, binder addition, and sintering conditions influence the film porosity, pore‐size distribution, light scattering, and electron percolation and consequently affect the solar‐cell efficiency.