The technology of organic electronics unlocks new ways to create semiconductor devices which are impossible using more conventional materials. The organic semiconductors at their heart can be simple to process, stable and non-toxic, and the variety of possible molecular designs is enormous. Organic light-emitting diodes (OLEDs) are the greatest success story within this sphere, since efficient light sources are a basic requirement for applications ranging from modern consumer electronics to small-scale battery-driven devices, and are a crucial driver for the uptake of off-grid technologies in the developing world. In this proposal, we seek to understand the conversion between different states of the species responsible for light emission in OLEDs, known as excitons. This can then be used to better design new molecules, particularly more efficient OLED molecules for emission in the blue.