Title: Electronic structure and non-linear optical properties of organic photovoltaic systems with potential applications on solar cell devices: A DFT approach,
Abstract: The use of eco-friendly materials for the environment has been addressed as a
critical issue in the development of systems for renewable energy applications.
In this regard, the investigation of organic photovoltaic (OPV) molecules for
the implementation in solar cells, has become a subject of intense research in
the last years. The present work is a systematic study at the B3LYP level of
theory performed for a series of 50 OPV materials. Full geometry optimizations
revealed that those systems with a twisted geometry are the most energetically
stable. Nuclear independent Chemical shifts (NICS) values show a strong
aromatic character along the series, indicating a possible polymerization in
solid-state, via a {\pi}-{\pi} stacking, which may be relevant in the design of
a solar cell device. The absorption spectra in the series was also computed
using Time Dependent DFT at the same level of theory, indicating that all
spectra are red-shifted along the series. This is a promissory property that
may be directly implemented in a photovoltaic material, since it is possible to
absorb a larger range of visible light. The computed HOMO-LUMO gaps as a
measurement of the band gap in semiconductors, show a reasonable agreement with
those found in experiment, predicting candidate materials that may be directly
used in photovoltaic applications. Non-linear optical (NLO) properties were
also estimated with the aid of a PCBM molecule as a model of an acceptor, and a
final set of optimal systems was identified as potential candidates to be
implemented as photovoltaic materials. The methodological approach presented in
this work may aid in the in silico assisted-design of OPV materials.