Does the donor-acceptor concept work for designing synthetic metals? 2. Theoretical investigation of copolymers of 4-(dicyanomethylene)-4H-cyclopenta[2,1-b : 3,4-b ']dithiophene and 3,4-(ethylenedioxy)thiophene


SALZNER U., Kose M. E.

JOURNAL OF PHYSICAL CHEMISTRY B, cilt.106, ss.9221-9226, 2002 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 106 Konu: 36
  • Basım Tarihi: 2002
  • Doi Numarası: 10.1021/jp020142a
  • Dergi Adı: JOURNAL OF PHYSICAL CHEMISTRY B
  • Sayfa Sayısı: ss.9221-9226

Özet

Density functional theory (DFT) calculations were performed on oligomers of 3,4-(ethylenedioxy)thiophene (EDOT), 4-(dicyanomethylene)-4H-cyclopenta[2,1-b:3,4-b']dithiophene (CDM), and co-oligomers (CDM/EDOT). Oligomer data were extrapolated to polymer values. Theoretical band gaps reproduce lambda(max) from UV spectroscopy for PEDOT and are about 1 eV larger than electrochemical band gaps lambda(max) of PCDM/EDOT is predicted to be 0.42 eV smaller than that of PEDOT and 0.15 eV smaller than that of PCDM. PCDM/EDOT has a wide valence and an extremely narrow conduction "band". It is probably better not to refer to these localized states as a band at all. This rationalizes the mobility ratio of 500 between p-type and n-type charge carriers and the low n-type conductivity of PCDM/EDOT. The lack of dispersion of the conduction band is due to the very different EAs of EDOT and CDM.