A multi-junction photovoltaic
cell device. The device includes a lower
cell and an upper
cell, which is operably coupled to the lower cell. In a specific embodiment, the lower cell includes a lower glass substrate material, e.g., transparent glass. The lower cell also includes a lower
electrode layer made of a reflective material overlying the
glass material. The lower cell includes a lower absorber layer overlying the lower
electrode layer. In a specific embodiment, the absorber layer is made of a
semiconductor material having a
band gap energy in a range of Eg=0.7 to 1 eV, but can be others. In a specific embodiment, the lower cell includes a lower window layer overlying the lower absorber layer and a lower transparent
conductive oxide layer overlying the lower window layer. The upper cell includes a p+ type transparent conductor layer overlying the lower transparent
conductive oxide layer. In a preferred embodiment, the p+ type transparent conductor layer is characterized by traversing
electromagnetic radiation in at least a
wavelength range from about 700 to about 630 nanometers and filtering
electromagnetic radiation in a
wavelength range from about 490 to about 450 nanometers. In a specific embodiment, the upper cell has an upper p type absorber layer overlying the p+ type transparent conductor layer. In a preferred embodiment, the p type conductor layer made of a
semiconductor material has a
band gap energy in a range of Eg=1.6 to 1.9 eV, but can be others. The upper cell also has an upper n type window layer overlying the upper p type absorber layer, an upper transparent
conductive oxide layer overlying the upper n type window layer, and an upper
glass material overlying the upper transparent conductive
oxide layer.