Low-Temperature Chemical Sintered TiO2 Photoanodes Based on a Binary Liquid Mixture for Flexible Dye-Sensitized Solar Cells

A chemically sintered and binder-free paste of TiO2 nanoparticles (NPs) was prepared using a binary-liquid mixture of 1-octanol and CCl4. The 1:1 (v/v) complex of CCl4 and 1-octanol easily interacted chemically with the TiO2 NPs and induced the formation of a highly viscous paste. The as-prepared binary-liquid paste (PBL)-based TiO2 film exhibited the complete removal of the binary-liquid and residuals with the subsequent low-temperature sintering (~150°C) and UV-O3 treatment. This facilitated the fabrication of TiO2 photoanodes for flexible dye-sensitized solar cells (f-DSSCs). For comparison purposes, pure 1-octanol-based TiO2 paste (PO) with moderate viscosity was prepared. The PBL-based TiO2 film exhibited strong adhesion and high mechanical stability with the conducting oxide coated glass and plastic substrates compared to the PO-based film. The corresponding low-temperature sintered PBL-based f-DSSC showed a power conversion efficiency (PCE) of 3.5%, while it was 2.0% for PO-based f-DSSC. The PBL-based low- and high-temperature (500°C) sintered glass-based rigid DSSCs exhibited the PCE of 6.0 and 6.3%, respectively, while this value was 7.1% for a 500°C sintered rigid DSSC based on a commercial (or conventional) paste.