For the fabrication of the TiO2 working electrode, a homogenous paste containing TiO2 semiconductor (0.5 g) and ethyl alcohol (0.4 mL, 96%, Merck) was prepared. The diameter of the used TiO2 nano powder (Sigma–Aldrich) was 21 nm. The paste was then cast onto the FTO glass (1 cm × 3 cm) using the doctor-blade method with the thickness of the TiO2 film maintained at 20 μm. For a strong bonding between the TiO2 film particles and the FTO glass [1] and [3], the TiO2 paste-coated FTO glass was sintered at 450 °C for 2 h [2] and [3] and subsequently cooled. Afterwards, the TiO2 working electrodes were immersed in the respective dye solutions for 24 h at room temperature, prior to the DSSC assembly.