Colloidal semiconductor nanocrystals (NCs) are solution processable semiconductors that because of their remarkably broad absorption, large tunability, and high stability under ambient conditions are suitable for optoelectronic device fabrication. Recently, several authors have reported that the use of short ligands to assemble NCs thin films allows overcoming the dichotomy between quantum confinement and the necessity of electrical transport. Power conversion efficiencies above 5% and fill factors of 60% under AM1.5 illumination are obtained with PbS NCs cross-linked with benzene-dithiols in a simple Schottky-like architecture [1, 2]. This record efficiency demonstrates that even by using the simplest device architecture, accurate post-synthetic treatments result in substantial improvements in the performance. The peculiar features of the material and device physics will be discussed and correlated with DFT simulations [3,4]. [1] K. Szendrei, W. Gomulya, M. Yarema, W. Heiss and M. A. Loi, Appl. Phys. Lett. 97, 203501 (2010). [2] C. Piliego, L. Protesescu, S. Z. Bisri, M. V. Kovalenko and M. A. Loi, Energy Environ. Sci. (in print). [3] K. Szendrei, M. Speirs, W. Gomulya, D. Jarzab, M. Manca, O. V. Mikhnenko, M. Yarema, B. J. Kooi, W. Heiss, and M. A. Loi, Adv. Funct. Mater. 22, 1598 (2012). [4] Elena Degoli, Nicola Spallanzani, Olivia Pulci, Stefano Ossicini, S.Z. Bisri, Maria A. Loi (in preparation).
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