Probing Disorder in 2CzPN using Core and Valence States

TL;DR

This study investigates how disorder affects the electronic structure of the TADF emitter 2CzPN using computational and experimental methods, providing insights into the influence of molecular environment and internal variations.

Contribution

It combines density functional theory and X-ray photoelectron spectroscopy to analyze disorder effects on core and valence states in 2CzPN, advancing understanding of TADF emitter behavior.

Findings

Good agreement between theoretical and experimental spectra

Disorder significantly influences electronic states

Method aids interpretation of complex spectra

Abstract

Molecules which exhibit thermally activated delayed fluorescence (TADF) show great promise for use in efficient, environmentally-friendly OLEDs, and thus the design of new TADF emitters is an active area of research. However, when used in devices, they are typically in the form of disordered thin films, where both the external molecular environment and thermally-induced internal variations in parameters such as the torsion angle can strongly influence their electronic structure. In this work, we use density functional theory and X-ray photoelectron spectroscopy to investigate the impact of disorder on both core and valence states in the TADF emitter 2CzPN. By simulating gas phase molecules displaying varying levels of disorder, we assess the relative sensitivity of the different states to factors such as varying torsion angle. The theoretical results for both core and valence states show good agreement with experiment, thereby also highlighting the advantages of our approach for interpreting experimental spectra of large aromatic molecules, which are too complex to interpret based solely on experimental data.