Microwave synthesis of size-controllable SnO2 nanocrystals for dye-sensitized solar cells

Abstract

A microwave hydrothermal synthesis of size-tunable SnO₂ nanocrystals is achieved by employing a SnCl₄ solution in a mixed ethanol–water solvent. A large increase in ethanol content to over 90%, as well as an increase in SnCl₄ concentration, is the key to successfully obtain highly crystallized and well dispersed SnO₂ particles as large as 26 nm, which can be determined by XRD and HR-TEM observations. Such well ripened SnO₂ crystals exhibit a good performance as photoelectrodes in dye-sensitized solar cells, resulting in an IPCE of around 70% when N719 dye is employed. The size dependent differences in photoelectrochemical properties are studied by SLIM-PCV measurements. The results indicate that fast electron transport occurs with the large SnO₂ crystals, owing to their low electron trap density and shallow distribution.