Scattering and Recombination of Two Triplet Excitons in polymer light-emitting diodes

TL;DR

This study investigates how two triplet excitons in conjugated polymers scatter and recombine, revealing mechanisms that produce singlet excitons, polarons, and biexcitons, with yields influenced by interchain coupling.

Contribution

It introduces a nonadiabatic evolution method based on an extended Su-Schrieffer-Heeger model to analyze exciton interactions in conjugated polymers.

Findings

Recombination produces singlet excitons, polarons, and biexcitons.

Yields of these products increase with interchain coupling strength.

Results align with experimental observations.

Abstract

The scattering and recombination processes between two triplet excitons in conjugated polymers are investigated by using a nonadiabatic evolution method, based on an extended Su-Schrieffer-Heeger model including interchain interactions. Due to the interchain coupling, the electron and/or hole in the two triplet excitons can exchange. The results show that the recombination induces the formation of singlet excitons, excited polarons and biexcitons. Moreover, we also find the yields of these products, which can contribute to the emission, increase with the interchain coupling strength, in good agreement with results from experiments.