Relationship between Carbon Nitride Structure and Exciton Binding Energies: A DFT Perspective

Sigismund Melissen, Tangui Le Bahers, Stephan N. Steinmann, Philippe Sautet

Research output: Contribution to journalArticlepeer-review

102 Scopus citations


Graphitic (g)-CxNyHz has become a popular element in photocatalytic water splitting cells. Recently, the crystal structures of completely polymerized g-C3N4 and incompletely polymerized g-C6N9H3 crystals based on the triazine and heptazine monomers have been characterized. In this manuscript we evaluate the atomic and electronic nature of these structures using DFT. The study revealed strongly corrugated structures for the fully polymerized g-C3N4 and planar structures for the incompletely polymerized g-C6N9H3. The exciton binding energies of the heptazine-based structures are lower than that of their triazine-based analogues and lower for the completely polymerized structures than their incompletely polymerized analogues. The rather low dielectric constant and charge mobilities result in high exciton binding energies and hence low dissociation probabilities for these excitons. This confirms the necessity of a morphology inspired by bulk heterojunction architectures to ensure efficient charge carrier generation. The studied compounds can be considered intermediates between typical inorganic and organic semiconductors in terms of their photoabsorption properties.
Original languageEnglish (US)
Pages (from-to)25188-25196
Number of pages9
JournalJournal of Physical Chemistry C
Issue number45
StatePublished - 2015
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2021-11-04
Acknowledged KAUST grant number(s): ENS 14.065, KAUST 1974-02
Acknowledgements: Funding for this work was provided by the King Abdullah University of Science and Techonology (KAUST), within the framework of Special Academic Partnership Program Water Splitting (projects ENS 14.065 and KAUST 1974-02). The authors gratefully acknowledge Dr. A. Winfer and Dr. I. Shore (KAUST Supercomputing Laboratory), the computational resources provided by l'Institut du developpement et des ressources en informatique scientifique (IDRIS, under project x2015080609) of the Centre Nationale de la Recherche Scientifique (CNRS), Prof. R. Orlando (University of Torino) for advice on the use of the CRYSTAL14 suite, and Prof. B. Lotsch (Max Planck Institute for Solid State Research), Dr. R. Kerber (Cambridge University), and Prof. K. Takanabe (KAUST) for valuable discussions on this topic.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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