Asymmetric Synthesis and Study of Platinum Metallahelicenes in Circularly Polarised Phosphorescent Organic Light Emitting Diodes (CP-PHOLEDs)

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Organic light emitting diodes (OLEDs) require an emissive electroluminescent layer of an organic semiconductor material located between two electrodes, where at least one of the electrodes is transparent. Such devices are revolutionising display technologies due to thin dimensions, faster switching and higher contrast ratios. Indeed, currently the market for such devices is valued at >$2.5B. Devices that emit circularly polarised electroluminescence (CPEL) should have vast translational potential in photonic technology, such as improved LCD backlighting, colour-image detection and stereoscopic displays, optical communication, and quantum computing, however to date the problem of directly generating CPEL has not been solved. Successful development of this technology is reliant on the production of light-emitting devices of controllable circular polarisation, tuneable emission wavelength, and high colour purity. While wide-band reflective polarisers may be used as passive components in OLED devices to achieve CPEL, the direct generation of CPEL would be far more elegant, and favourable in terms of energy efficiency and production cost. This research will develop efficient methods to synthesise intrinsically chiral phosphorescent molecules and use these to fabricate CP electroluminescent devices, in an attempt to demonstrate highly efficient CPEL. The successful direct generation of circularly polarised electroluminescence (CPEL) would have a transformative effect on a range of disciplines including physics and materials science. Such work would have significant impact on current knowledge, which could be exploited in a number of translational areas. The UK is a pioneer of OLED technology and needs new innovation to maintain this position. Indeed, former chief scientific advisor Sir David King has recognised this potential highlighting "in Britain we have a world-leading position in a technology that could wipe out the silicon chip" "I am talking about plastic electronics". Taking alternative LCD backlighting as one example of the exploitation of this work, current technologies rely on polarising filters that effectively cut out 75% of the light used in these displays. Combined with absorption by the colour filters and at device interfaces, only 4% of the light used is transmitted. The use of a polarised light source, coupled with tuneable colour components would remove this need, thus leading to significantly more energy efficient displays. Such displays with a lowered carbon footprint would be of clear environmental impact.