Synthesis of TiO2 by hydrothermal method using deep eutectic solvent for application in dye-sensitised solar cell

Raw TiO2 powder from a commercial source was used as a precursor in the hydrothermal process with deep eutectic solvent (DES) of choline chloride and urea with a molar ratio of 1:2 at different temperatures and interval times. The synthesised TiO2 was further utilised to produce diffracting TiO2 paste for application in dye-sensitised solar cells (DSCs) to improve the power conversation efficiency of devices. The TiO2 product analysed by X-ray diffraction (XRD) showed a similar phase and crystallinity to the raw material. However, scanning electron microscope (SEM) images showed that the hydrothermal TiO2 product had less particle aggregation than the raw one. The particle size was exceedingly 100 nm. The TiO2 pastes were prepared with a mixture of ethyl acetate and terpineol at volume ratios of 3:7 and 4:6. The paste was suitable to make thin films by the screen-printing method as a diffusion layer in cells. DSC devices using the TiO2 produced by the hydrothermal process with DES at 140oC for 18, 24, and 36 hours, respectively, enhanced the power conversion efficiency by 6.7-6.9%, which was higher than the ones using raw TiO2 by about 7%. Therefore, TiO2 powder modified by the hydrothermal process in DES solvent has great potential for application in DSC manufacture.