Communication: Tailoring the optical gap in light-harvesting molecules

A. Karolewski, T. Stein, R. Baer, S. Kümmel*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

109 Scopus citations


Systematically varying the optical gap that is associated with charge-transfer excitations is an important step in the design of light-harvesting molecules. So far the guidance that time-dependent density functional theory could give in this process was limited by the traditional functionals' inability to describe charge-transfer excitations. We show that a nonempirical range-separated hybrid approach allows to reliably predict charge-transfer excitations for molecules of practically relevant complexity. Calculated absorption energies agree with measured ones. We predict from theory that by varying the number of thiophenes in donor-acceptor-donor molecules, the energy of the lowest optical absorption can be tuned to the lower end of the visible spectrum. Saturation sets in at about five thiophene rings.

Original languageAmerican English
Article number151101
JournalJournal of Chemical Physics
Issue number15
StatePublished - 21 Apr 2011

Bibliographical note

Funding Information:
We acknowledge discussions with A. Neubig, M. Thelakkat, and T. Körzdörfer, and finanical support by Deutsche Forschungsgemeinschaft(DFG) GRK1640 and the GIF.


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