Charge separation in donor-C60 complexes with real-time Green's functions: The importance of nonlocal correlations

E. Viñas Boström; A. Mikkelsen; C. Verdozzi; E. Perfetto; G. Stefanucci

doi:10.1021/acs.nanolett.7b03995

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arXiv · 1801.07712

Charge separation in donor-C60 complexes with real-time Green's functions: The importance of nonlocal correlations

E. Viñas Boström·A. Mikkelsen·C. Verdozzi·E. Perfetto·G. Stefanucci

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Abstract

We use the Nonequilibrium Green's Function (NEGF) method to perform real-time simulations of the ultrafast electron dynamics of photoexcited donor-C60 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 non-local correlation corrections are included. This CS process occurs in ~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 indicate 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.

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E. Viñas Boström, A. Mikkelsen, C. Verdozzi, E. Perfetto, G. Stefanucci. 2018-01-23. Charge separation in donor-C60 complexes with real-time Green's functions: The importance of nonlocal correlations. https://doi.org/10.1021/acs.nanolett.7b03995

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