Tailoring the electronic properties of semiconducting nanocrystal-solids

An overview of the recent progress made in the synthesis of colloidal semiconducting nanocrystals (NCs), with particular emphasis on applications for solar cell materials is provided. Peculiar phenomena in NCs, such as multiple exciton generation and intermediate-band absorption are described as important mechanisms to improve the efficiency of the third-generation solar cells. The state of art and challenges to exploit these effects in NCs based materials are highlighted. We focus on two complementary approaches that are very promising: the synthesis of core/shell NCs and the incorporation of these NCs into semiconducting matrices, thus creating a fully inorganic quantum dot solid. We also show two examples of inorganic quantum dot solids, one using Si or Ge NCs and another employing InAs or InP NCs. For the latter, a joint experimental and theoretical study is reviewed, showing how quantum dot solids introduce new concepts and need for a new way of thinking different than that just summing up the effects and properties of NCs and the semiconducting hosting matrix.