Investigation of exciton transport in crystalline thin-films of the organic semiconductor di-indeno-perylene using photoluminescence analyses

TL;DR

This study investigates exciton transport in crystalline di-indeno-perylene thin films using photoluminescence, revealing temperature-dependent coherent and incoherent transport regimes and correlating diffusion length with structural coherence.

Contribution

It introduces an advanced exciton diffusion model accounting for interference, quencher penetration, and non-ideal quenching, applied to DIP to elucidate exciton transport mechanisms.

Findings

Exciton diffusion length is about 90 nm, correlating with structural coherence.

Transport is incoherent above 80 K and coherent below 80 K.

Temperature influences exciton transport regime and phonon interactions.

Abstract

The exciton transport in the prototypical organic semiconductor Di-Indeno-Perylene (DIP) has been investigated by means of photoluminescence (PL) quenching and interpreted by an advanced exciton diffusion model including interference effects, quencher penetration as well as non-perfect exciton quenching. X-ray difraction revealed a correlation between the exciton diffusion length of about 90 nm and the structural coherence length of the DIP layers. Temperature dependent studies in a range of 5 - 300 K indicated an incoherent exciton transport above 80 K at activation energies of 10 - 20 meV related to the thickness dependent gradient of exciton density. Below 80 K a coherent exciton transport can be observed by the reduced phonon-interaction at cryogenic temperatures. This manuscript is a pre-final version.