Electronic structure and non-linear optical properties of organic photovoltaic systems with potential applications on solar cell devices: A DFT approach

摘要

The use of eco-friendly materials for the environment has been addressed as acritical issue in the development of systems for renewable energy applications.In this regard, the investigation of organic photovoltaic (OPV) molecules forthe implementation in solar cells, has become a subject of intense research inthe last years. The present work is a systematic study at the B3LYP level oftheory performed for a series of 50 OPV materials. Full geometry optimizationsrevealed that those systems with a twisted geometry are the most energeticallystable. Nuclear independent Chemical shifts (NICS) values show a strongaromatic character along the series, indicating a possible polymerization insolid-state, via a {\pi}-{\pi} stacking, which may be relevant in the design ofa solar cell device. The absorption spectra in the series was also computedusing Time Dependent DFT at the same level of theory, indicating that allspectra are red-shifted along the series. This is a promissory property thatmay be directly implemented in a photovoltaic material, since it is possible toabsorb a larger range of visible light. The computed HOMO-LUMO gaps as ameasurement of the band gap in semiconductors, show a reasonable agreement withthose found in experiment, predicting candidate materials that may be directlyused in photovoltaic applications. Non-linear optical (NLO) properties werealso estimated with the aid of a PCBM molecule as a model of an acceptor, and afinal set of optimal systems was identified as potential candidates to beimplemented as photovoltaic materials. The methodological approach presented inthis work may aid in the in silico assisted-design of OPV materials.