% G4 (red curve). The electrodes listed in the order of active absorption area are G4-doped photoelectrode > G2-doped photoelectrode > pristine TiO2 photoelectrode. The absorption spectra indicate that more photon energy could be harvested. The effective spectrum ranges

from 375 to 900 nm. These spectra cover a UV-visible-IR region. The emission spectra of G2 and G4 are shown in Figure 2b, which was obtained by excitation at 254 nm with the emission line at 517 nm for G2 and excitation at 288 nm with the emission line at 544 nm for G4. To determine the optimal contents of the dopant, optoelectric and electrochemical technology were used. The optimal content of green phosphor was 5 wt.%. Figure 2 Absorption of TiO 2 electrode and CP673451 manufacturer emission spectra of G2 and G4. (a) Absorption spectra of pristine TiO2 electrode. TiO2 electrode doped with 5 wt.% of G2, and TiO2 electrode doped with 5 wt.% of G4. (b) Emission spectra of G2 and G4. Figure 3 shows electrochemical impedance spectroscopy measurements for pristine, G2-doped, and G4-doped TiO2 photoelectrode. In these observations, the Nyquist plots of the impedance characteristics were obtained from the dependence of the real axis resistance (Z re) and imaginary axis AZD5582 mouse resistance (Z im) along with the angular frequency. The diameter of the first semicircle at

middle frequency illustrated in the spectra shows the charge-transfer resistance (R ct) between the TiO2 (or doped TiO2 with G2 and G4) and electrolyte.

The bulk resistances (R s) of the pristine, G2-doped, and G4-doped TiO2 electrodes are 12.8, 13.7, and 13.4 Ω, respectively. The R ct values of the pristine, G2-doped, and G4-doped TiO2 electrode devices are 26.3, 21.9, and 19.8 Ω, respectively. In the case of G4-doped TiO2 devices, smaller R ct means a decrease in interfacial resistance and an increase of energy conversion efficiency. The results show a significant effect on the internal resistance of the solar cell and, consequently, can affect the fill factor and conversion efficiency. Figure 3 Nyquist plot of the impedance characteristics between Z re and Z im . It is with the angular frequency ω = 2πf of pristine TiO2 electrode and TiO2 electrode doped with 5 wt.% of G2 and TiO2 electrode doped with 5 wt.% of G4. The incident photon-to-current conversion efficiency LY294002 (IPCE) spectra show the cell of a pristine TiO2 photoelectrode doped with 5 wt.% G2 and 5 wt.% G4. The pristine TiO2 photoanode exhibits a maximum IPCE value of 55% at 530 nm, while for the cell with TiO2 photoanode doped with G2 and G4, the peaks reach 65% and 70%, respectively, as shown in Figure 4. Moreover, an increase of IPCE value in the range of 550 to 650 nm for the cells with doped G2 and G4 photoanodes are observed due to the scattering effect of the G2 and G4 materials, which favor the improvement of J sc for the cell [19].