Band-like transport, high electron mobility and high photoconductivity in all-inorganic nanocrystal arrays

Flexible, thin-film electronic and optoelectronic devices typically involve a trade-off between performance and fabrication cost 1 , 2 , 3 . For example, solution-based deposition allows semiconductors to be patterned onto large-area substrates to make solar cells and displays, but the electron mobility in solution-deposited semiconductor layers is much lower than in semiconductors grown at high temperatures from the gas phase 4 . Here, we report band-like electron transport in arrays of colloidal cadmium selenide nanocrystals capped with the molecular metal chalcogenide complex 5 , 6 In 2 Se 4 2− , and measure electron mobilities as high as 16 cm 2 V −1 s −1 , which is about an order of magnitude higher than in the best solution-processed organic 7 and nanocrystal 8 devices so far. We also use CdSe/CdS core–shell nanoparticles with In 2 Se 4 2− ligands to build photodetectors with normalized detectivity D * > 1 × 10 13 Jones (I Jones = 1 cm Hz 1/2 W −1 ), which is a record for II – VI nanocrystals. Our approach does not require high processing temperatures, and can be extended to different nanocrystals and inorganic surface ligands. Arrays of cadmium selenide nanocrystals capped with molecular metal chalcogenide complexes exhibit high values of electron mobility and photoconductivity.