Blue TiO2 polymorph: An efficient material for dye-sensitized solar cells fabricated using a low-temperature sintering process

Abstract

Recently, surface-disordered or non-stoichiometric TiO2, such as blue TiO2 (B-TiO2), has received much attention owing to its unique properties, such as structural disorder near the surface and the existence of Ti3+ ions and oxygen vacancies. Therefore, surface-disordered TiO2 has been applied for microwave absorption, photocatalysis, in photoelectrochemical sensors and rechargeable lithium-ion batteries. In this work B-TiO2, a polymorph consisting of nanoparticles, nanotubes and nanosheets, was successfully synthesized and employed as a semiconductor layer in dye-sensitized solar cells (DSSCs) fabricated using a low-temperature heat treatment process (120 °C). Based on the analyses of the experimental results regarding the structure and those from the characterization of B-TiO2, and its application to DSSCs, it has been found that the B-TiO2 material has an effect on electron-hole pair separation. The conversion efficiency of the B-TiO2 DSSC (BTiO2-DSSC) was 6.18%, whereas that of the TiO2-P25 DSSC (P25-DSSC) was 3.61%, and that of the TiO2 polymorph DSSC (PTiO2-DSSC) which is the precursor of B-TiO2 was 4.51%.