Compared with typical QDSSCs based on other narrow bandgap semiconductors (e.g., CdS and CdSe), the V oc values of Ag2S-QDSSCs THZ1 are quite low which are almost equivalent to half of

the others (CdS-QDSSCs, 0.6 to 0.7 V). Despite of the high J sc values owing to a broad absorption spectrum, η is limited by the low V oc values. When t p was elongated to 15 min, η decreases sharply with a halving J sc and a lower Fill factor (FF). This phenomenon is speculated to be caused by too long deposition time which results in excess Ag2S nanoparticles generated on TiO2 NRs, consequently decreases effective electron injection and increases recombination rate. The slightly reduced FF as t p increases also indicates that recombination rate rises with growing amount of loading Ag2S nanoparticles. Figure 7 J – V characteristics of solar cells fabricated with different photoanodes under AM 1.5 illumination at 100 mW/cm 2 . Table 1 Photovoltaic parameters of solar cells fabricated with different photoanodes under AM 1.5 illumination at 100 mW/cm 2 Solar cell J sc(mA/cm2) V oc(V) FF η (%) Bare TiO2 1.34 0.32 0.30 0.13 3 min 4.15 0.24

0.42 0.41 5 min 9.00 0.27 0.38 0.83 10 min 10.25 0.29 0.32 0.98 15 min 4.71 0.28 0.29 0.38 The J-V curves of a Ag2S QD-sensitized solar cell measured at three different light intensities are shown in Figure 8. The photovoltaic performance parameters are listed in Table 2. The η reaches a value of 1.25% MGCD0103 in vitro at 47 mW/cm2 solar intensity. The J sc value accumulates to 11.7 mA/cm2 as incident light intensity increases to 150 mW/cm2 (150% sun). However, J sc produced by per unit light power is decreased by a factor of 40.9 compared with lower light level condition of 47% sun. This suggests

that the incident light is not effectively converted into electricity at a higher photon density, which may be attributed to a lower rate of photon capture due to the insufficient QDs loading on TiO2 nanorods. By employing longer TiO2 NRs, the response of the photocurrent should be promoted to be linear with the incident light intensity, and a higher 17-DMAG (Alvespimycin) HCl conversion efficiency should be reached at full sunlight. Figure 8 J – V curves of Ag 2 S QD-sensitized solar cell measured at different light intensities. Table 2 Photovoltaic parameters of Ag 2 S QD-sensitized solar cell measured at different light intensities P in(mW/cm2) J sc(mA/cm2) V oc(V) FF η (%) 150 11.7 0.3 0.37 0.87 100 10.3 0.29 0.33 0.98 47 6.2 0.26 0.36 1.23 38 4.6 0.25 0.32 0.97 The photostability of Ag2S-QDSSC was measured by illuminating it at 100 mW/cm2 sunlight for 2 h and characterized by recording the J sc and V oc of the device (Figure 9). During illumination, the J sc remained relatively Akt inhibitor steady with a drop less than 5%, and the V oc fluctuated within 2%.