Molecules relevant for organic photovoltaics: a range-separated density functional study

Abstract

Accurate determination of both fundamental and optical gap is necessary for designing molecules relevant for organic photovoltaics. Here, we study how range-separated density functionals reproduce frontier orbital energies, HOMO (highest occupied molecular orbital)–LUMO (lowest unoccupied molecular orbital) gaps, and optical gaps for molecules relevant for organic photovoltaics. In this study, we consider 12 different range-separated density functional for computing HOMO energy, HOMO–LUMO gap, and optical gap which are compared with available experimental and reported GW values. We found that the reproduction of desired photovoltaic properties primarily depend on range separation parameter. Moreover, the tested functionals are comparable with OT-BNL functional.

Keywords:

• organic photovoltaics
• range-separated density functionals
• HOMO–LUMO gap
• optical gap

Acknowledgements

The authors are grateful to Xavier Blase (CNRS, Institut Néel, CNRS and University Joseph Fourier, Grenoble) for providing the optimised geometries. Manash Protim Borpuzari acknowledges the Council of Scientific and Industrial Research (CSIR), New Delhi for his research fellowship. The numerical calculations were partly conducted on the RIKEN Cluster of Clusters (RICC).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The research was supported by SERB, Department of Science and Technology (DST), New Delhi [grant number SB/FT/CS-132/2013] (Rahul Kar); the Japan Society for the Promotion of Science (JSPS) KAKENHI [grant number 23225001] (Kimihiko Hirao) and [grant number 26410030] (Jong-Won Song).