InP/ZnS core-shell quantum dots sensitized ZnO nanowires for photovoltaic devices

With the increasing worldwide need for energy, fossil fuels will not be able to keep up with demand in the coming decades. Solar energy is one of the best solutions to this problem with the advantages of being clean and sustainable. Among the various designs of solar cells, dye-sensitized solar cells provide relatively high efficiency with large scale for a low cost [1]. Conventional dye-sensitized solar cells operate with light harvesting organic dye molecules adsorbed at the interface between TiO₂ nanoparticles and a hole-conducting liquid electrolyte [2]. However, new combinations of materials potentially present an opportunity to further improve the performance and lower the cost of solar cells. One such promising approach is to use quantum dots (QDs) instead of the organic materials as the main photosensitive constituent. Several types of semiconductor QDs, including CdSe [3], CdS [4] and InP [5], have been investigated to realize quantum dot sensitized solar cells by taking advantage of the tunable absorption spectrum of the QDs through changes in their size. Complementarily to this approach, it is desirable to use a semiconductor material with a high structural uniformity and surface area as the framework on which to attach these QDs and achieve efficient electron transport, such as well-aligned ZnO nanowires [6].