Semiconductor-Sensitized Mesoscopic Solar Cells: From TiO2 to SnO2

Abstract

In this thesis, firstly, an investigation on band alignment of cascade CdS/CdSe-sensitized electrodes unambiguously reveals that the CdS is redundant and impedes the injection of electrons from CdSe to metal oxides and accelerates charge recombination at the metal oxide/sensitizer interface. Secondly, CdSxSe1-x-sensitized electrodes with tunable band gap energies were synthesized and explored in SSCs. Thirdly, mesoscopic SnO2 was investigated as an alternative photoanode to the commonly used TiO2 and was found to be superior, exhibiting an unprecedented photocurrent density and nearly unity IPCE because of long electron diffusion lengths and superior charge separation yield compared with TiO2-based SSCs. Fourthly, utilizing the lower CBM and greater affinity of the SnO2 for the growth of PbS, cascaded PbS/CdS-sensitized SnO2-based cells exhibited infrared light harvesting extending beyond 1100 nm. Finally, SnO2 nanostructures with tunable shape and size were synthesized by a post-treatment of nanoparticles obtained from electrochemical anodization of tin foil.