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Photoconductivity of CdTe Nanocrystal-Based Thin Films: Te2– Ligands Lead To Charge Carrier Diffusion Lengths Over 2 μm

Research paper by Ryan W. Crisp, Rebecca Callahan, Obadiah G. Reid, Dmitriy S. Dolzhnikov, Dmitri V. Talapin, Garry Rumbles, Joseph M. Luther, Nikos Kopidakis

Indexed on: 23 Nov '15Published on: 16 Nov '15Published in: Journal of Physical Chemistry Letters



Abstract

We report on photoconductivity of films of CdTe nanocrystals (NCs) using time-resolved microwave photoconductivity (TRMC). Spherical and tetrapodal CdTe NCs with tunable size-dependent properties are studied as a function of surface ligand (including inorganic molecular chalcogenide species) and annealing temperature. Relatively high carrier mobility is measured for films of sintered tetrapod NCs (4 cm2/(V s)). Our TRMC findings show that Te2– capped CdTe NCs show a marked improvement in carrier mobility (11 cm2/(V s)), indicating that NC surface termination can be altered to play a crucial role in charge-carrier mobility even after the NC solids are sintered into bulk films.

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