期刊
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
卷 12, 期 6, 页码 2843-2852出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jctc.6b00217
关键词
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资金
- Spanish Grants [FIS2012-37549-C05-02, FIS2013-46159-C3-1-P, RYC-2011-09582, JCI-2010-08156]
- Generalitat de Catalunya [2014SGR301]
- Grupos Consolidados UPV/EHU del Gobierno Vasco [IT-578-13]
Optimizing the photovoltaic efficiency of dye-sensitized solar cells (DSSC) based on staggered gap heterojunctions requires a detailed understanding of sub-band gap transitions in the visible from the dye directly to the substrates conduction band (CB) (type-II DSSCs). Here, we calculate the optical absorption spectra and spatial distribution of bright excitons in the visible region for a prototypical DSSC, catechol on rutile TiO2(110), as a function of coverage and deprotonation of the OH anchoring groups. This is accomplished by solving the BetheSalpeter equation (BSE) based on hybrid range-separated exchange and correlation functional (HSE06) density functional theory (DFT) calculations. Such a treatment is necessary to accurately describe the interfacial level alignment and the weakly bound charge transfer transitions that are the dominant absorption mechanism in type-II DSSCs. Our HSE06 BSE spectra agree semiquantitatively with spectra measured for catechol on anatase TiO2 nanoparticles. Our results suggest deprotonation of catechols OH anchoring groups, while being nearly isoenergetic at high coverages, shifts the onset of the absorption spectra to lower energies, with a concomitant increase in photovoltaic efficiency. Further, the most relevant bright excitons in the visible region are rather intense charge transfer transitions with the electron and hole spatially separated in both the [110] and [001] directions. Such detailed information on the absorption spectra and excitons is only accessible via periodic models of the combined dye-substrate interface.
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