Comment on On the Yield of Singlet Excitons in Organic Light-Emitting Devices: a Double Modulation Photoluminescence-Detected Magnetic Resonance Study

TL;DR

This paper critically examines the origin of spin 1/2 photoluminescence-detected magnetic resonance in conjugated polymers, challenging previous claims that it arises from triplet exciton interactions.

Contribution

It demonstrates that spin 1/2 PLDMR in MEH-PPV and similar polymers is independent of triplet exciton density, providing new insights into the underlying mechanisms.

Findings

Spin 1/2 PLDMR does not depend on triplet exciton density.

The origin of PLDMR is not linked to triplet excitons in conjugated polymers.

Previous interpretations associating PLDMR with triplet excitons are challenged.

Abstract

In a recent Letter Lee et al. studied the spin 1/2 photoluminescence-detected magnetic resonance (PLDMR) of a soluble derivative of poly-phenylene vinylene [MEH-PPV] and argued that it originates from the interaction of triplet excitons with polarons. We show that in MEH-PPV as well as in other conjugated polymers the spin 1/2 PLDMR does not depend on the triplet exciton density and thus cannot be associated with triplet excitons.