Theory of Electric Field-Induced Photoluminescence Quenching in Disordered Molecular Solids

TL;DR

This paper develops a theoretical model to explain how electric fields cause photoluminescence quenching in disordered molecular solids, highlighting exciton dissociation mechanisms and matching experimental observations.

Contribution

The paper introduces a theoretical framework that accounts for exciton migration, recombination, and dissociation under electric fields, explaining PL quenching in doped polymers.

Findings

Electric field strength influences PL quenching significantly.

Dissociation mechanisms differ between conjugated polymer blends and doped polymers.

Model accurately reproduces experimental PL quenching data.

Abstract

The dynamics of excitons in disordered molecular solids is studied theoretically, taking into account migration between different sites, recombination, and dissociation into free charge carriers in the presence of an electric field. The theory is applied to interpret the results of electric field-induced photoluminescence (PL) quenching experiments on molecularly doped polymers by Deussen et al. [Chem. Phys. 207, 147 (1996)]. Using an intermolecular dissociation mechanism, the dependence of the PL quenching on the electric field strength and the dopant concentration, and the time evolution of the transient PL quenching can be well described. The results constitute additional proof of the distinct exciton dissociation mechanisms in conjugated polymer blends and molecularly doped polymers.