2. Computational Details
The analytical solution to the problems related to structural
modifications and modeling of photoinjection in organic dyes is a
cumbersome task. Thanks to the development of different commercial codes
and upgradation of computational infrastructures in recent past, the
numerical solution to such problems with high reliability, precision and
reproducibility are now possible. This work was carried out using LCAO
(linear combination of atomic orbitals) based approach implemented in
DFT code ADF (Amsterdam Density Functional) version 2018 which performs
DFT, time dependent DFT (TD-DFT) [51] and Density-Functional based
tight binding (DFTB) calculations [52] by computationally employing
formulism of Kohn-Sham theory in fast and efficient way [53].
In order to investigate the effects of structural modification of
carbazole-donor based organic dye on photoinjection, three dyes, named
here as D1, D2 and D3 , shown in figure 2, were used as reference
[23]. The length of the π-spacer of
carbazole-donor based organic dye with oligothiophene π-spacer having
carboxylic acid as acceptor was increased by adding thiophene units.