Optimisation of ultrafast singlet fission in 1D rings towards unit efficiency

TL;DR

This paper demonstrates how to optimize ultrafast singlet fission in 1D ring systems using non-perturbative numerical methods, achieving efficiencies over 85% in coherent regimes and up to 99% with exciton-phonon tuning, with implications for optoelectronic devices.

Contribution

It introduces a non-perturbative numerical approach to optimize singlet fission in 1D rings, surpassing previous efficiency limits and providing a framework for broader optoelectronic optimization.

Findings

Achieved over 85% singlet fission efficiency in non-dissipative regimes.

Reached up to 99% efficiency when tuning exciton-phonon interactions.

Identified two classes of solutions for optimal singlet fission performance.

Abstract

Singlet fission (SF) is an electronic transition that in the last decade has been under the spotlight for its applications in optoelectronics, from photovoltaics to spintronics. Despite considerable experimental and theoretical advancements, optimising SF in materials like multichromophoric systems and molecular crystals remains a challenge, due to the complexity of its analysis beyond perturbative methods. Here, we tackle the case of 1D rings, aiming to promote singlet fission and prevent its back-reaction. We study ultrafast SF non-perturbatively, by numerically solving a spin-boson model, via exact propagation and tensor network methods. By optimising over a parameter space relevant to organic molecular materials, we identify two classes of solutions that can take SF efficiency beyond 85% in the non-dissipative (coherent) regime, and to 99% when exciton-phonon interactions can be tuned. After discussing the experimental feasibility of the optimised solutions, we conclude by proposing that this approach can be extended to a wider class of optoelectronic optimisation problems.