Volume 216, 2019

Quantum coherence in ultrafast photo-driven charge separation

Abstract

Coherent interactions are prevalent in photodriven processes, ranging from photosynthetic energy transfer to superexchange-mediated electron transfer, resulting in numerous studies aimed towards identifying and understanding these interactions. A key motivator of this interest is the non-statistical scaling laws that result from coherently traversing multiple pathways due to quantum interference. To that end, we employed ultrafast transient absorption spectroscopy to measure electron transfer in two donor–acceptor molecular systems comprising a p-(9-anthryl)-N,N-dimethylaniline chromophore/electron donor and either one or two equivalent naphthalene-1,8:4,5-bis(dicarboximide) electron acceptors at both ambient and cryogenic temperatures. The two-acceptor compound shows a statistical factor of 2.1 ± 0.2 rate enhancement at room temperature and a non-statistical factor of 2.6 ± 0.2 rate enhancement at cryogenic temperatures, suggesting correlated interactions between the two acceptors with the donor and with the bath modes. Comparing the charge recombination rates indicates that the electron is delocalized over both acceptors at low temperature but localized on a single acceptor at room temperature. These results highlight the importance of shielding the system from bath fluctuations to preserve and ultimately exploit the coherent interactions.

Graphical abstract: Quantum coherence in ultrafast photo-driven charge separation

Associated articles

Supplementary files

Article information

Article type
Paper
Submitted
30 Nov 2018
Accepted
08 Jan 2019
First published
08 Jan 2019

Faraday Discuss., 2019,216, 319-338

Author version available

Quantum coherence in ultrafast photo-driven charge separation

B. T. Phelan, J. D. Schultz, J. Zhang, G. Huang, Ryan M. Young and M. R. Wasielewski, Faraday Discuss., 2019, 216, 319 DOI: 10.1039/C8FD00218E

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