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Semiconductor quantum dots (QDs) and single-walled carbon nanotubes (SWNTs) are ideal building blocks for the design of optoelectronic devices, such as photodetectors. QDs exhibit tunable optical properties due to the quantum size effect, whereas SWNTs show ideal charge transport behavior. The combination of both is assumed to be a powerful tool for constructing new materials.[1,2] In this work, PbSe QDs were used as the light absorbing material. PbSe QDs are of particular interest due to their narrow band gap and large excitonic Bohr radius, which makes them highly sensitive to near-infrared light. Coupling PbSe QDs to SWNTs transforms the excitonic state, generated by photoexcitation of the QDs, into a charge separated state. The fast charge transport in SWNTs leads to enhanced photocurrents. Therefore, stable PbSe/SWNT heterostructures are promising materials for the design of efficient near-infrared photodetectors.[2,3] Quasi-monodisperse PbSe QDs with different particle sizes are routinely obtained using the hot-injection method.[4] Adding dispersed SWNTs to the lead precursor solution and subsequent direct growth of the QDs on the SWNTs sidewalls resulted in PbSe/SWNT hybrids without any linker groups. Pure PbSe QDs and PbSe/SWNT heterostructures were characterized by high-resolution transmission electron microscopy and Raman spectroscopy. Their current-voltage characteristics were investigated in the dark and under illumination. [1] Manga, K. K.; Wang, J.; Lin, M.; Zhang, J.; Nesladek, M.; Nalla, V.; Ji, W.; Loh, K. P. Adv. Mater. 2012, 24, 1697-1702. [2] Cho, N.; Choudhury, K. R.; Thapa, R. B.; Sahoo, Y.; Ohulchanskyy, T.; Cartwright, A. N.; Lee, K.-S.; Prasad, P. N. Adv. Mater. 2007, 19, 232. [3] Wang, D.; Baral, J. K.; Zhao, H.; Gonfa, B. A.; Truong, V.-V.; Khakani, M. A. E.;Izquierdo, R.; Ma, D. Adv. Funct. Mater. 2011, XX, 1. [4] Yu, W. W.; Falkner, J. C.; Shih, B. S.; Colvin, V. L. Chem. Mater. 2004, 16, 3318-3322. |
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