30-nm AZO deposited on pristine and faceted silicon. It is observed that the photoresponsivity reduces in the case of the latter one in the projected wavelength range. Different parameters such as short-circuit current densities (J SC), open-circuit voltages (V

OC), and FF for the above samples are summarized in Table  1 under air mass 0 and 1 sun illumination condition for other AZO thicknesses as well. The FF is defined as FF = (V M J M)/ (V OC J SC), where V M J M is the maximum power density. From Table  1, one can see that the FF increases by a factor of 2 in the case of AZO overlayer grown SN-38 supplier on faceted silicon as compared to the one on pristine silicon, whereas V OC is found to be half the value obtained from the latter one. In addition, J SC becomes 1 order of magnitude higher in the case of AZO-coated faceted silicon, and the same trend is followed for higher AZO thicknesses. From Table  1, it is observed that the FF reaches maximum at 60-nm AZO on faceted silicon (0.361) as compared to others. This improvement in FF can be attributed to the effective light trapping in the visible Sapitinib region in the case of conformally grown AZO films on nanofaceted silicon template [21]. This would ensure the usage of more photogenerated power, leading to an increase in the cell efficiency. Such enhancement in light trapping

selleck compound is found to be directly associated with the enhanced AR property of the same film (inset of Figure  5). However, the reduced V OC can be attributed to the existence of defect centers in the native oxide at the AZO/Si interface and ion beam-produced traps on silicon facets. It may be mentioned that AZO/Si heterostructures, PDK4 in general, yield low FF values and can be improved by using nanofaceted silicon substrates [22]. Thus, our experimental results suggest that besides tunable AR property (Figure  4), FF can also be improved by adjusting the AZO overlayer thickness.

Figure 5 RT photoresponsivity. Photoresponsivity spectra of 30-nm-thick AZO overlayer grown on planar and nanofaceted Si in the spectral range of 300 to 800 nm. The inset shows the optical reflectance spectra for these two samples mentioned above. Table 1 Different photovoltaic parameters obtained from various AZO overlayer thicknesses grown on silicon substrates Sample J SC(mA/cm2) V OC(V) FF 30-nm AZO on pristine Sia 1.24 × 10-3 0.133 0.142 30-nm AZO on nanofaceted Si 3.0 × 10-2 0.075 0.279 60-nm AZO on nanofaceted Si 5.35 × 10-2 0.087 0.361 75-nm AZO on nanofaceted Si 37.57 × 10-2 0.055 0.252 aHigher AZO thicknesses (beyond 30 nm) deposited on planar silicon substrate did not show any significant photoresponsivity. Compared to the inverted pyramid approach [23, 24], which yields reflectance values between 3% and 5% for an optimized AR coating thickness between 400 and 1,000 nm, our results show a better (by a factor of 10) performance with a smaller (30 to 75 nm) AZO film thickness.