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Photocatalytic activity and the radiative lifetimes of excitons via ab initio approach


This work presents the radiative lifetimes of photogenerated electron-hole (e-h) pairs in bulk anatase and rutile TiO2 calculated by solving the Bethe-Salpeter equation (BSE) at the G0W0 level with Perdew-Burke-Ernzerhof (PBE) as starting point, an approach labeled as PBE-G0W0-BSE. The geometry optimization and the electronic ground state are determined by PBE. G0W0, considered as the "gold standard" for band structure calculations, provides band gap results of anatase and rutile in good agreement with experimental values. By solving BSE that surmounts the single-particle picture of individual quasielectron and quasihole excitation, the approach for calculating radiative lifetime shakes off the dependence on the band structure in DFT calculations and the renormalization factors in many GW calculations. For anatase, the calculated intrinsic lifetime of the lowest optically active bright excitons turns out to be several microseconds, while those of rutile is few picoseconds. Overall, the e-h lifetimes of anatase are several orders of magnitude longer than those of rutile, showing good agreement with the experimentally measured values. Longer lifetimes of excitons in anatase lead to observed better photocatalytic activity of these two common TiO2 phases. The ab initio calculation approach for e-h lifetime is thus shown to be a predictive and convenient tool for designing novel materials with potential applications in photonics and optoelectronics.

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Publication details

The article was received on 04 May 2018, accepted on 11 Jul 2018 and first published on 11 Jul 2018

Article type: Communication
DOI: 10.1039/C8TA04140G
Citation: J. Mater. Chem. A, 2018, Accepted Manuscript
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    Photocatalytic activity and the radiative lifetimes of excitons via ab initio approach

    L. Hu, C. xu, L. Peng, F. L. Gu and W. Yang, J. Mater. Chem. A, 2018, Accepted Manuscript , DOI: 10.1039/C8TA04140G

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