Abstract
Polymers with low optical gaps are of importance to the organic photovoltaics community due to their potential for harnessing a large portion of the solar energy spectrum. The combination along their backbones of electron-rich and electron-deficient fragments contributes to the presence of low-lying excited states that are expected to display significant charge-transfer character. While conventional hybrid functionals are known to provide unsatisfactory results for charge-transfer excitations at the time-dependent DFT level, long-range corrected (LRC) functionals have been reported to give improved descriptions in a number of systems. Here, we use such LRC functionals, considering both tuned and default range-separation parameters, to characterize the absorption spectra of low-optical-gap systems of interest. Our results indicate that tuned LRC functionals lead to simulated optical-absorption properties in good agreement with experimental data. Importantly, the lowest-lying excited states (excitons) are shown to present a much more localized nature than initially anticipated.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 14243-14248 |
| Number of pages | 6 |
| Journal | Physical Chemistry Chemical Physics |
| Volume | 14 |
| Issue number | 41 |
| DOIs | |
| State | Published - Nov 7 2012 |
| Externally published | Yes |
Bibliographical note
KAUST Repository Item: Exported on 2020-10-01Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: This work has been supported by the National Science Foundation under the STC Program (Award No. DMR-0120967) and under the CRIF Program (Award No. CHE-0946869) and by the Center for Advanced Molecular Photovoltaics (Award No. KUS-C1-015-21 made by King Abdullah University of Science and Technology, KAUST).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- General Physics and Astronomy
- Physical and Theoretical Chemistry