Organic light-emitting diodes (OLEDs) have emerged as a state-of-the-art technology for displays and lighting as illustrated by their presence in the majority of recent smartphone designs. However, despite this success there remains a need to improve the performance and sustainability of these devices. The key part of an OLED device is the emission layer which usually consists of small organic molecule emitters embedded within a thin film of host material. While most commercial products are based on fluorescent and phosphorescent emitters, much academic interest has shifted towards materials harnessing other mechanisms, such as thermally activated delayed fluorescence (TADF) and consequently these molecules and materials have been studied extensively both experimentally 1,2 and computationally in recent years. Computational modelling can provide an accurate description of the singlet and triplet excited-state manifolds and explain structural and electrostatic effects on the properties of the emitting layer, which in turn can assist with designing better TADF materials.