Chemical design for high performance blue organic light-emitting diodes

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The lack of a high performance blue Light Emitting Diode (LED) has been a bottleneck in the scientific community since the advent of artificial lighting technologies. However, in 2014 the Nobel Prize in Physics was awarded to Akasaki, Amano, and Nakamura for their contribution to the development of the long-awaited highly efficient blue LED based on Gallium Nitride (GaN). However, despite the many successes of inorganic semiconductor technology in the electronics industry, these devices can be costly and difficult to fabricate. Instead, the field of plastic electronics utilises organic semiconductor materials which are more cost-effective, processable from solutions at low temperatures, and effectively infinitely tuneable through the alteration of their unique molecular structures. Despite the relative ease in the development of the red and green Organic LED (OLED), the blue OLED still suffers from short lifetimes and a lack of colour purity, which ultimately hinders the commercialisation of novel device architectures and competitiveness with alternative technologies. Since 2015, a new class of molecular materials known as Multi-Resonant Thermally Activated Delayed Fluorescence (MR-TADF) emitters have been of significant interest because they can afford deep-blue devices with high efficiencies and colour purity. However, they are also currently limited by their short lifetimes. Herein, we propose to provide greater insight into the photophysics underlying the degradation of MR-TADFs through combining a molecular encapsulation synthetic strategy and optical spectroscopy studies. It is hoped that a greater understanding of the photophysics will better place us to rationally design higher performing novel materials and reduce the use of 'trial-and-error' approaches seen within the field.