Exciton Dynamics on Rubrene (001) Crystal Surfaces with Microstructure Confinement

TL;DR

This study investigates exciton behavior on rubrene crystal surfaces and pyramids, revealing how microstructure confinement influences exciton states, diffusion, and decay dynamics through spatially resolved photoluminescence analysis.

Contribution

It provides new insights into exciton dynamics under microstructured confinement, including quantification of diffusion constants and activation barriers.

Findings

Exciton ratios depend on structural size and optical absorption profiles.

Estimated exciton diffusion constant is at least 0.2 cm²/s at 4 K.

Activation barriers between exciton states are 3 meV and 14 meV.

Abstract

The exciton dynamics on flat (001) rubrene crystal surfaces have been compared with those under confined pyramidal geometry by time-resolved photoluminescence with micrometer spatial resolution. The luminescence spectra can be interpreted in terms of generation of a free and a self-trapped exciton. Their ratio depends significantly on the structural size which we explain by the optical absorption profile of the pyramids in combination with the exciton diffusion constant. For the latter a lower limit of 0.2 cm2/s at 4 K has been estimated. Temperature-dependent decay times reveal activation barriers between free and self-trapped exciton of 3 meV and 14 meV.