Theory of photoinduced charge transfer in weakly coupled donor-acceptor conjugated polymers: application to an MEH-PPV:CN-PPV pair

TL;DR

This paper develops a theoretical model to analyze photoinduced charge transfer rates between weakly coupled donor-acceptor conjugated polymers, specifically applied to MEH-PPV and CN-PPV pairs, revealing how decay times vary with inter-polymer distance.

Contribution

The study introduces a theoretical framework for calculating exciton decay rates in weakly coupled conjugated polymer pairs, with specific application to MEH-PPV and CN-PPV, highlighting distance-dependent charge transfer dynamics.

Findings

Decay time at 6 Å is 2.2 ps.

Decay time at 4 Å is approximately 50 fs.

Charge transfer rate increases significantly as inter-polymer distance decreases.

Abstract

In a pair of coupled donor-acceptor conjugated polymer chains, it is possible for an exciton photoexcited on either polymer to decay into a hole in the donor polymer's valence band and an electron in the conduction band of the acceptor polymer. We calculate the corresponding exciton decay rate and its dependence on inter-polymer distance. For a pair of derivatives of poly(phenylene vinylene), PPV, specifically poly[2-methoxy, 5-(2$^\prime$-ethyl-hexyloxy)-1, 4 PPV], MEH-PPV, and poly(2,5-hexyloxy $p$-phenylene cyanovinylene), CN-PPV, at a separation of 6 \AA the characteristic decay time is 2.2 ps, whereas at 4 \AA it is $\sim 50$ fs.