Organic light emitting diodes (OLEDs) show promise for the future of display and lighting electronics, but current commercial OLED emitters suffer from several shortcomings. In particular, the efficiency of first- generation fluorescent emitters is limited to just 25% due to spin statistics. This limitation was overcome by second-generation phosphorescent emitters which incorporate heavy metals and can achieve an efficiency of 100%. However, these materials are both costly and harmful to the environment. Third-generation emitters, namely thermally activated delayed fluorescence emitters (TADF), present a solution to such issues as they can achieve 100% efficiency and are fully organic. Considerable research efforts have therefore been dedicated over the last decade to the discovery of new emitters of this type and mechanisms by which their structures can be designed and optimised. Computational chemistry plays an important role in elucidating how ideal TADF properties arise as a result of structural features, without the need for time-consuming and costly experimental trial and error. High-throughput virtual screening (HTVS) approaches focus on the computational design of emitter molecules through a process of elimination by calculating key properties governing TADF and progressively filtering out candidates. This thesis presents research involving analysis of the effectiveness of an existing HTVS workflow for the discovery of new TADF emitters and their design rules, discusses improvements made, further analysis of its results, and highlights potential directions for future work. In particular, alterations and additions were made to initial cheminformatics filters and force field pre- optimisation of structures in terms of the methods used as well as filter thresholds, based on analysis in this research. Similar changes were made to the following stages involving density functional theory calculations for the study of excited state properties, overall leading to several promising potential candidates for TADF and suggestions for their structure-property relations.
A High-Throughput Virtual Screening Approach for the Discovery of Thermally Activated Delayed Fluorescence Emitters and their Design Rules
Jones, J. (Author). 17 Jun 2025
Student thesis: Master's Thesis › Master of Science by Research (MScR)