Spin selective charge recombination in chiral donor-bridge-acceptor triads

Thomas P Fay; David T Limmer

doi:10.1063/5.0150269

Spin selective charge recombination in chiral donor-bridge-acceptor triads

J Chem Phys. 2023 May 21;158(19):194101. doi: 10.1063/5.0150269.

Authors

Thomas P Fay¹, David T Limmer^{1

2

3

4}

Affiliations

¹ Department of Chemistry, University of California, Berkeley, California 94720, USA.
² Kavli Energy Nanoscience Institute at Berkeley, Berkeley, California 94720, USA.
³ Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
⁴ Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.

PMID: 37184005
DOI: 10.1063/5.0150269

Abstract

In this paper, we outline a physically motivated framework for describing spin-selective recombination processes in chiral systems, from which we derive spin-selective reaction operators for recombination reactions of donor-bridge-acceptor molecules, where the electron transfer is mediated by chirality and spin-orbit coupling. In general, the recombination process is selective only for spin-coherence between singlet and triplet states, and it is not, in general, selective for spin polarization. We find that spin polarization selectivity only arises in hopping-mediated electron transfer. We describe how this effective spin-polarization selectivity is a consequence of spin-polarization generated transiently in the intermediate state. The recombination process also augments the coherent spin dynamics of the charge separated state, which is found to have a significant effect on the recombination dynamics and to destroy any long-lived spin polarization. Although we only consider a simple donor-bridge-acceptor system, the framework we present here can be straightforwardly extended to describe spin-selective recombination processes in more complex systems.