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Keywords:

  • photovoltaics;
  • nanoparticles;
  • silicon thin films;
  • adsorption;
  • photoexcitations

Abstract

Systems composed of small Ag clusters adsorbed on the Si(111):H surface have been computationally studied by methods of density functional theory (DFT) and time-dependent DFT, to obtain information on properties of photoexcitations and electronic structure. The systems have been modeled as slabs with varying numbers of layers, and an increasing number of Ag atoms in the adsorbed clusters. Ab initio electronic structure, atomic conformations, excitation energies, electron binding energies, and electronic oscillator strengths are obtained using two different implementations of DFT, as provided by the Vienna Ab-initio Simulation Package and Gaussian03 computational packages. Time-independent results from extended and finite models establish a general trend regarding the energy band gaps increase with slab thickness and decrease with cluster sizes. Resulting trends in oscillator strength versus photon energies, from time-dependent calculations, establish a consistent picture with an increase of light absorption at the lower photon energies as the size of clusters and number of slab layers is increased. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009