25-cm2 FTO glass substrate. Glass-FTO/TiO2 and phosphor-doped TiO2 electrodes
were immersed overnight (ca. 24 h) in a 5 × 10−4 mol/L ethanol solution of Ru(dcbpy)2(NCS)2 (535-bis TBA, Solaronix), rinsed with anhydrous ethanol, and dried. A few drops of the liquid electrolyte were dispersed onto the surface, and a full cell assembly was constructed for electrochemical measurements. A Pt-coated FTO electrode was prepared as a counter electrode with an active area of 0.25 cm2. The Pt electrode was placed buy EPZ-6438 over the dye-adsorbed TiO2 thin film electrode, and the edges of the cell were sealed with 5-mm wide strips of 60-μm-thick sealing sheet (SX 1170–60, Solaronix). Sealing was accomplished by hot-pressing the two electrodes together at 110°C. Characterization of DSSC The surface morphology of the film was observed by FE-SEM (S-4700, Hitachi High-Tech, Minato-ku, Tokyo, Japan). A 450-W xenon lamp was used as light source
for generating a monochromatic beam. Calibration was performed using a silicon photodiode, which was calibrated using an NIST-calibrated photodiode G425 as a standard. UV-visible (vis) spectra of the TiO2 film and TiO2 electrode with green phosphor powder added were measured with a UV–vis spectrophotometer (8453, Agilent Technologies, Inc., Santa Clara, CA, USA). Photoluminescence spectra were recorded on Avantes BV (Apeldoorn, The Netherlands) spectrophotometer under the excitation of Nd:YAG laser beam (355 nm). Electrochemical impedance spectroscopies of the DSSCs were measured with an electrochemical workstation (CHI660A, CH Instruments Inc., TX, USA). The photovoltaic properties were investigated by measuring CB-839 order the current density-voltage (J-V) characteristics
under irradiation of white light Clomifene from a 450-W xenon lamp (Thermo Oriel Instruments, Irvine, CA, USA). Incident light intensity and active cell area were 100 mW cm−2 and 0.25 cm2, respectively. Results and discussion Figure 1 shows FE-SEM cross-sectional images of a TiO2 electrode doped with 5 wt.% of G2 (Figure 1a), G2 powder (Figure 1b), and a TiO2 electrode doped with 5 wt.% G4 (Figure 1c) and G4 powder (Figure 1d). The size of the two green phosphor powder particles varied from 3 to 7 μm without uniformity. These nonuniform micro-sized structures of the fluorescent powder could create porous and rough surface morphologies on the surface of and within the TiO2 photoelectrode. However, the maximum doping ratio was 5 wt.%. This type of structure has advantages for the adsorption of a higher percentage of dye molecules and also supports deeper penetration of the I-/I3 – redox couple into the TiO2 photoelectrode. Figure 1 Cross-sectional FE-SEM images of TiO 2 electrode. It is doped with 5 wt.% of G2 (a), G2 powder (b), TiO2 electrode doped with 5 wt.% of G4 (c), and G4 powder (d). Figure 2a shows the absorption spectra of a pristine TiO2 photoelectrode (black curve), a TiO2 photoelectrode doped with 5 wt.