Semiconducting Oligomers of 1,4-dimethoxybenzene, Thiophene and Thiazole: A Theoretical Study | Chapter 1 | Theory and Applications of Chemistry Vol. 2
Organic semiconducting
oligomers containing three to nine heterocyclic units and based on 1,4-dimethoxybenzene,
thiophene and thiazole have been studied by DFT and TDDFT at the
B3LYP/6-31G(d,p) level. The energy
of each molecule,
those of the frontier orbitals HOMO and
LUMO,the width of the
band gaps and
the optical properties
have been calculated. The inter-ring distances,
dihedral angles and torsional angles have been elucidated. These molecules are
planar π-conjugated systems. The
band gaps of
the longer oligomers
studied range from
2.53 to 2.72
eV and their excitation energies
calculated by TDDFT
vary from 2.22
to 2.36 eV. Wavelengths of absorption bands of 524 to
556 nm are also obtained by TDDFT. The results of this theoretical study show
that these organic molecules have interesting properties and can potentially be
used as components in solar cells. In this work, a theoretical investigation on
the geometries and optoelectronic properties of oligomers based on
1,4-dimethoxybenzene, thiophene and thiazole has been done. Molecules that
contain up to nine rings have been studied. For all these oligomers, the
elongation of the molecular chain led to a gradual decrease of the energy gap
between the frontier orbitals. This energy splitting varied from 2.5 to 3.7 eV.
This indicates that these compounds may exhibit semi-conducting properties. The
increase in the
molecular chain length also induced
a decrease in
the excitation energy determined
by TDDFT. These oligomers present many intra and inter-unit interactions which
contribute to their rigidity and to a better delocalization of the π-electrons.
Author(s) Details
Diendéré Françoise
Laboratoire de Chimie Moléculaire et des Matériaux, Université de Ouagadougou, UFR/SEA 03 BP 7021, Burkina Faso.
Laboratoire de Chimie Moléculaire et des Matériaux, Université de Ouagadougou, UFR/SEA 03 BP 7021, Burkina Faso.
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