Charge Transport and Interfacial Charge Transfer in Dye-Sensitized Nanoporous Semiconductor Electrode Systems

Abstract

General characteristics of dye-sensitized nanoporous semiconductor electrode systems are summarized, with a particular emphasis on dye-sensitized solar cells. Properties of these electrode systems which distinguish them from conventional bulk semiconductor electrodes are highlighted. Current understanding of electron transport in dye-sensitized solar cells, in terms of the diffusion and multiple trapping models, is reviewed. Alternative transport and recombination theories are also briefly reviewed. Electron transfer at the semiconductor/electrolyte interface in dye-sensitized solar cells is reviewed and recent experimental results obtained by the authors are highlighted. As applicable, common techniques for characterization of electron transport and transfer in dye-sensitized solar cells are described, with reference to case studies where the electron diffusion length in dye-sensitized solar cells has been estimated. The steady-state aspects of the dye-regeneration process are also reviewed, together with the cross-surface percolation of holes in the dye monolayer and the finite-length diffusion of redox species in the electrolyte.