Abstract
Solid films of colloidal quantum dots show promise in the manufacture of photodetectors and solar cells. These devices require high yields of photogenerated charges and high carrier mobilities, which are difficult to achieve in quantum-dot films owing to a strong electron–hole interaction and quantum confinement. Here, we show that the quantum yield of photogenerated charges in strongly coupled PbSe quantum-dot films is unity over a large temperature range. At high photoexcitation density, a transition takes place from hopping between localized states to band-like transport. These strongly coupled quantum-dot films have electrical properties that approach those of crystalline bulk semiconductors, while retaining the size tunability and cheap processing properties of colloidal quantum dots.
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Acknowledgements
This work was supported by SenterNovem (project SELECT) and the Netherlands Organisation for Scientific Research (NWO), Division of Chemical Sciences (VICI award 700.53.443). The 3TU Centre for Sustainable Energy Technologies is acknowledged for financial support. A.J.H. acknowledges financial support through a NWO-VENI grant. The authors thank S. Patwardhan for useful discussions and M. Murra for the photograph of the film.
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E.T. and A.J.H. designed the experiment, analysed data and wrote the paper. E.T. performed TRMC experiments. Y.G. and M.A. synthesized the quantum dots and developed the film preparation procedure. Y.G. performed transient absorption measurements and simulations of the mobility. L.K. performed terahertz conductivity experiments. T.J.S. designed the temperature-dependent TRMC setup. J.M.S. developed the analytical deconvolution procedure. M.v.H. performed TEM experiments. H.S.J.v.d.Z. and L.D.A.S. gave conceptual advice.
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Talgorn, E., Gao, Y., Aerts, M. et al. Unity quantum yield of photogenerated charges and band-like transport in quantum-dot solids. Nature Nanotech 6, 733–739 (2011). https://doi.org/10.1038/nnano.2011.159
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DOI: https://doi.org/10.1038/nnano.2011.159
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