Figure 6 Photocurrent eFT508 in vitro density-voltage curves and variation of conversion efficiency. Photocurrent density-voltage curves of 3-D selenium ETA solar cells (a) and the variation of conversion efficiency (b) with different CH5424802 mw TiO2 particle sizes used for the porous TiO2 layer. The annotation numbers

in Figure 6a suggest the sizes of the nanocrystalline TiO2 particle utilized for the electrodes. Figure 7 shows the photocurrent density-voltage curves and the variation of the conversion efficiency of 3-D selenium ETA solar cells with HCl concentrations in the solution for depositing selenium. The TiO2 nanoparticle with a 60-nm diameter was utilized for the porous layer, and the concentration of H2SeO3 was kept at 20 mM. From Figure 6a, the photocurrent density increased

with the increase in HCl concentration in the range of 2.9 to 11.5 mM and decreased with HCl concentration of over 11.5 mM. The cells deposited at HCl concentrations of 11.5 and 17.3 mM showed a higher V OC than those that were prepared at 2.9 and 8.6 mM HCl. Figure 6b shows the variation of the conversion efficiency with an HCl concentration BIRB 796 in the ECD solution. The highest conversion efficiency was obtained at the concentration of 11.5 mM. In the case of samples deposited with the concentrations of 2.9 and 8.6 mM HCl, Se was almost observed at the outer porous TiO2; this is the reason for getting a low cell performance. Conversely, Se distributed uniformly from the bottom to the top of porous TiO2 at an HCl concentration

of 11.5 mM. Further addition of HCl (17.3 mM) caused the deposition rate of Se to become rather fast and the porous-TiO2 layer to easily break and fall off from the substrate; this can explain the low cell performance of samples depositing at 17.3 mM HCl. Figure 7 Photocurrent density-voltage curves and variation of the conversion efficiency of 3-D selenium ETA solar cells. Photocurrent density-voltage curves (a) and the variation of conversion efficiency (b) of 3-D selenium ETA solar cells with different HCl concentrations. The annotation numbers in Figure 7a suggest the HCl concentrations Ureohydrolase for Se deposition. In order to investigate the effect of H2SeO3 concentration on the cell performance, cells were prepared at various H2SeO3 concentrations. Figure 8 depicts the photocurrent density-voltage curves with different H2SeO3 concentrations. The HCl concentration in these experiments was kept at 11.5 mM, and 60-nm TiO2 nanoparticles were utilized for the porous layer. From the results, the photovoltaic performance of cells is seemingly better at a lower H2SeO3 concentration. The best cell performance was observed at 20 mM H2SeO3.