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We present experiments on the optoelectronic properties of two-dimensional gold nano-particle arrays, including bolometric [1], plasmonic [2], and Coulomb blockade induced phenoma [3]. In addition, we report on a molecular phototransistor effect based on conjugated molecules incorporated in such nanoparticle arrays [4]. We find a pronounced photoconductance arising upon resonant excitation of the molecules. We determine the typical response time and the irradiation intensity dependence of this resonant photoconductance. Our results suggest that the charge carriers, which are resonantly excited in the OPV molecules, directly contribute to the current flow through the nanoparticle arrays. We consistently model the dynamics of the resonant photoconductance by considering the filling and recombination of trap states in the nanoparticle arrays. Our results verify that individual molecules in metal-molecule-metal junctions can be functional modules of optoelectronic devices. We acknowledge the very fruitful collaboration with M. Mangold, J. Schopla, N. Erhard, M. Calame, and M. Mayor. [1] M. A. Mangold, C. Weiss, M. Calame, and A. W. Holleitner, Applied Physics Letters 94, 161104 (2009). [2] M. Mangold, C. Weiss, B. Dirks, A.W Holleitner, Applied Physics Letters 98, 243108 (2011). [3] M. Mangold, M. Calame, M. Mayor, A.W. Holleitner, ACS Nano (2012). [4] M. Mangold, M. Calame, M. Mayor, A.W. Holleitner, J. Am. Chem. Soc. 133, 12185-12191 (2011). |
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