Most OLED materials need several layers to provide a flow of electrons and ‘holes’, or spaces where electrons can move into, and other layers to stop the flow of electrons or holes in the right places. But the new molecule improves on current OLED designs by performing several necessary electronic functions in just one layer. It can also be treated to emit all the colours required for laptop and mobile phone displays.
The new molecule comprises a quinoxaline group, which accepts electrons very readily, and bulky polyphenyl groups, which stop the molecules sticking together and losing energy by nonradiative pathways – this means it can take the place of several layers in the OLED. A pixel made from the new material, which can emit red, green and blue light, allows OLED devices to comprise only two layers.
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