Figure 1

(a) Stacking of PbS layers of different band gaps allows absorption of a wider range of solar spectrum. The wider band gap layer absorbs short wavelength photons while the longer wavelength photons are transmitted through it to reach the narrow band gap PbS. The schematic of the approach is also given. (b) Proposed utilization scheme of solar spectrum. (c) Typical transmittance of the CdS/FTO/Glass and absorption coefficient of PbS thin films with band gaps of 0.92 and 1.61 eV. Stacking of 0.92 eV band gap PbS thin film improves absorption range of solar spectrum.