Spatially composition-graded alloy semiconductor nanowires and wavelength specific lateral-multijunction full-spectrum solar cells

We demonstrate chemical vapor deposition of single crystal Zn_xCd_1-xSySe_1-y alloy nanowires with continuous spatial composition-grading (x and y from 0 to1) across a single wafer, resulting in a controlled spatial bandgap variation from ~ 3.6 eV (ZnS) to ~ 1.7eV (CdSe). To take advantage of this unprecedented material capability for photovoltaic applications, we analyzed several designs of lateral multijunction solar cells, where incoming solar light is spectrally dispersed, such that each wavelength band is incident onto a region of the wafer with the corresponding bandgap. Such designs have potential of realizing large numbers of junctions to allow the full potential of many junctions to be explored for high-efficiency dispersive concentration photovoltaics.