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Keywords:

  • density functional;
  • nanotube;
  • photovoltaic;
  • effective mass;
  • polymer

Abstract

One major approach for efficient photovoltaic devices based on polymeric materials lies in the use of bulk heterojunctions, which mix two different organic polymeric materials acting as donor and acceptor semiconductors. In these bulk heterojunctions the donor polymer typically acts as the light absorber, creating an electron-hole pair and then donating the excited electron to the acceptor polymer. A deep theoretical understanding of the physical processes at work in these materials will require a knowledge of the electron states near the Fermi level for both the donor and acceptor. Bulk heterojunction systems based on mixtures of single-wall carbon nanotubes and poly(3-octylthiophene) have recently been reported in the literature. We calculate the electronic structure for both semiconducting and metallic single-wall nanotubes, and compare these with electronic structure results for poly(3-methylthiophene) as a model for the poly(3-alkyl-thiophenes). We also present results for the effective mass of single-wall carbon nanotubes and poly(3-methyl-thiophene) using the calculated electronic band structures. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007