Graphitic carbon nitrides form a popular family of materials, particularly as photoharvesters in photocatalytic water splitting cells. Recently, relatively ordered g-C3N4 and g-C6N9H3 were characterized by X-ray diffraction and their ability to photogenerate excitons was subsequently estimated using density functional theory. In this study, the ability of triazine-based g-C3N4 and g-C6N9H3 to photogenerate excitons was studied using self-consistent GW computations followed by solving the Bethe–Salpeter Equation (BSE). In particular, monolayers, bilayers and 3D-periodic systems were characterized. The predicted optical band gaps are in the order of 1 eV higher than the experimentally measured ones, which is explained by a combination of shortcomings in the adopted model, small defects in the experimentally obtained structures and the particular nature of the experimental determination of the band gap.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): ENS 14.065, KAUST 1974-02
Acknowledgements: Funding for this work was provided by King Abdullah University of Science and Technology (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 Développement et des Ressources en Informatique Scientifique (IDRIS, under project x2015080609) of the Centre National de la Recherche Scientifique (CNRS) and by the Pôle Scientifique de Modélisation Numérique (PSMN) at ENS Lyon.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.