We use the nonequilibrium Green function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C-60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent density matrix renormalization group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical nonlocal correlation corrections are included. This CS process occurs in similar to 10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicates that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.

Bostrom, E.v., Mikkelsen, A., Verdozzi, C., Perfetto, E., Stefanucci, G. (2018). Charge separation in donor-C-60 complexes with real-time green functions: the importance of nonlocal correlations. NANO LETTERS, 18(2), 785-792 [10.1021/acs.nanolett.7b03995].

Charge separation in donor-C-60 complexes with real-time green functions: the importance of nonlocal correlations

Perfetto E.;Stefanucci G.
2018-01-01

Abstract

We use the nonequilibrium Green function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C-60 complexes modeled by a Pariser-Parr-Pople Hamiltonian. The NEGF results are compared to mean-field Hartree-Fock (HF) calculations to disentangle the role of correlations. Initial benchmarking against numerically highly accurate time-dependent density matrix renormalization group calculations verifies the accuracy of NEGF. We then find that charge-transfer (CT) excitons partially decay into charge separated (CS) states if dynamical nonlocal correlation corrections are included. This CS process occurs in similar to 10 fs after photoexcitation. In contrast, the probability of exciton recombination is almost 100% in HF simulations. These results are largely unaffected by nuclear vibrations; the latter become however essential whenever level misalignment hinders the CT process. The robust nature of our findings indicates that ultrafast CS driven by correlation-induced decoherence may occur in many organic nanoscale systems, but it will only be correctly predicted by theoretical treatments that include time-nonlocal correlations.
2018
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore FIS/03 - FISICA DELLA MATERIA
English
Bostrom, E.v., Mikkelsen, A., Verdozzi, C., Perfetto, E., Stefanucci, G. (2018). Charge separation in donor-C-60 complexes with real-time green functions: the importance of nonlocal correlations. NANO LETTERS, 18(2), 785-792 [10.1021/acs.nanolett.7b03995].
Bostrom, Ev; Mikkelsen, A; Verdozzi, C; Perfetto, E; Stefanucci, G
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/208766
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