The coordination chemistry of nanocrystal surfaces

Abstract

In the 1990s, when quantum confined colloidal semiconductor nanocrystals (NCs, or quantum dots) were first synthesized with narrow size distributions, there was an explosion of effort to harness their bright and narrow luminescence for optoelectronic devices and fluorescence labeling (1). However, the surfactant ligands that stabilized NCs also influenced their electronic structure and optical properties. Encapsulating the NC cores within an insulating inorganic shell reduced the effect of surface structure on charge recombination (2) and forced the radiative recombination of photoexcited charges. These structures greatly increased the photoluminescence quantum yield (PLQY) and enabled their recent use in liquid crystal displays. However, PLQYs of core-shell nanocrystals remain sensitive to their surfaces and if NCs are to be useful within electrical devices, such as photovoltaic (PV) cells, the complex relation between their surface structure and their frontier orbital structure must be better understood.