n-type conducting CdSe nanocrystal solids

A bottleneck limiting the widespread application of semiconductor nanocrystal solids is their poor conductivity. We report that the conductivity of thin films of n-type CdSe nanocrystals increases by many orders of magnitude as the occupation of the first two electronic shells, 1S(e) and 1P(e), increases, either by potassium or electrochemical doping. Around half-filling of the 1S(e) shell, a peak in the conductivity is observed, indicating shell-to-shell transport. Introducing conjugated ligands between nanocrystals increases the conductivities of these states to similar to10(-2) siemens per centimeter.