2 to 3.3 eV. In the visible range, the
transmittance of the FTO covered with ZnO decreases slightly with the increase of ZnO film thickness. For instance, it decreases to approximately 95% of the transmittance of the bare FTO for 20-nm-thick ZnO. Therefore, the presence of ZnO layer with the thickness less than 20 nm will not obviously influence the harvest of light. The inset in Figure 3b is the SEM photo of FTO substrate covered with 15-nm-thick ZnO film, which shows that the ZnO film deposited by ALD method keeps the surface morphology of FTO substrate very well. Figure 3 XRD patterns. ZnO DihydrotestosteroneDHT layers deposited on glass substrate (a) and UV–vis ��-Nicotinamide manufacturer transmission spectra for the FTO substrate without and with ZnO layers (b). The inset in b is the SEM photo of FTO substrate covered with 15-nm-thick ZnO film. Performance of DSSCs The influence of sintering temperature of TiO2 nanofiber photoanodes on the performance of TiO2 nanofiber cells Cells I to III are TiO2 nanofiber cells (sintered at 500°C, 550°C, and 600°C) on the bare FTO substrates. Based on the above photocurrent-voltage(J V) measurement results, a thickness of approximately 40 μm was set to fabricate cells I to III. Figure 4 illustrates the J V characteristics of TiO2 nanofiber cells under AM 1.5 irradiation of 100 mW cm−2. The photovoltaic properties such as short-circuit current density
(J sc), open-circuit voltage (V oc), fill factor (FF), and Cediranib nmr photoelectric conversion efficiency (PCE) of the cells are listed in Table 1. Cell I has a J sc of 15.1 mA cm−2, PCE of 6.39%, V oc of 0.814 V, and fill factor (FF) of 0.52. When sintering temperature increased from 500°C to 550°C, cell II gave an improvement of J sc and V oc about 1.2 mA cm−2 and 11 mV, respectively, resulting in an efficiency of 7.12%. However, the further increase of sintering temperature decreased J sc, V oc, and PCE of cell III to 14.1 mA cm−2, 0.818 V, and 6.11%, respectively. According to the
XRD data, rutile contents of TiO2 nanofibers Isotretinoin are approximately 0, 15.6, and 87.8 wt.% in cells I, II, and III, respectively. The J V measurement results demonstrate that the anatase-rutile mixed-phase TiO2 nanofiber with a low rutile content is good for enhancing efficiencies of the DSSCs, whereas a high rutile content is detrimental to the efficiencies, which is similar to the reported DSSCs based on mixed-phase TiO2 nanoparticles [19, 20]. Figure 4 Photocurrent-voltage characteristics of cells I to III under AM 1.5 irradiation of 100 mW cm −2 . Based on TiO2 nanofibers sintered at 500°C, 550°C, and 600°C. Table 1 Photocurrent density-voltage characteristics of TiO 2 nanofiber cells sintered at 500°C, 550°C, and 600°C Cell Temperature (°C) J sc(mA/cm2) V oc(V) FF η (%) τ d(ms) τ n(ms) L n(μm) I 500 15.1 0.814 0.52 6.39 3.36 55.3 74.2 II 550 16.3 0.825 0.53 7.12 1.88 107.7 138.3 III 600 14.1 0.818 0.