Abstract
Flexible, thin-film electronic and optoelectronic devices typically involve a trade-off between performance and fabrication cost1,2,3. 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 phase4. Here, we report band-like electron transport in arrays of colloidal cadmium selenide nanocrystals capped with the molecular metal chalcogenide complex5,6 In2Se42−, and measure electron mobilities as high as 16 cm2 V−1 s−1, which is about an order of magnitude higher than in the best solution-processed organic7 and nanocrystal8 devices so far. We also use CdSe/CdS core–shell nanoparticles with In2Se42− ligands to build photodetectors with normalized detectivity D* > 1 × 1013 Jones (I Jones = 1 cm Hz1/2 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.
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Acknowledgements
The authors thank P. Guyot-Sionnest, E. Shevchenko and D. Mitzi for stimulating discussions, E. Wong and R. Citron for help with the photoconductivity measurements, B. Lee for small angle X-ray scattering measurements at the beamline 12-ID-C at the Advanced Photon Source, S. Rupich for assistance with SEM, M. Bodnarchuk for dynamic light scattering and electrophoretic mobility measurements and S. Ithurria for help with synthesis of CdSe nanocrystals. The work was supported by the Office of Naval Research (award no. N00014-10-1-0190) and a National Science Foundation CAREER award (no. DMR-0847535). D.V.T. thanks the David and Lucile Packard Foundation for their generous support. The work at the Center for Nanoscale Materials (ANL) was supported by the Department of Energy (contract no. DE-AC02-06CH11357). Use of the Advanced Photon Source at Argonne National Laboratory was supported by the DOE, Office of Basic Energy Sciences (contract no. DE-AC02-06CH11357).
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J.S.L. and D.S.C. carried out device fabrication, performed charge transport measurements, analysed the data and co-wrote the paper. M.V.K. synthesized CdSe nanocrystals and inorganic ligands and carried out ligand exchange. J.H. synthesized CdSe/CdS nanocrystals. D.V.T. conceived and designed the experiments, helped with measurements, analysed the data and co-wrote the paper. All authors discussed the results and commented on the manuscript.
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Lee, JS., Kovalenko, M., Huang, J. et al. Band-like transport, high electron mobility and high photoconductivity in all-inorganic nanocrystal arrays. Nature Nanotech 6, 348–352 (2011). https://doi.org/10.1038/nnano.2011.46
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DOI: https://doi.org/10.1038/nnano.2011.46
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