Missing your partner can lead to all sorts of weird behaviours. It seems that this is true also for subatomic particles, and my research centres on developing ways of harnessing these quirks for efficient solar cells and light sources.
The structure of every chemical around us is determined by the way their tiny electrons are arranged. Quantum mechanics determines the allowed ladder of states that the electrons fill. Normally, they do it two-at-a-time, rung-by-rung from bottom to top, and it’s only the very topmost filled rung that matters for any process: a chemical reaction, or light generation.
This principle has been carefully exploited for decades in development of organic diodes (OLEDs) for displays and lighting. Unfortunately, the rules of the ladder work against achieving the required high brightness, with at least 75% of electricity needed to power the device being wasted. This happens due to the quarrelsome relationship each pair of electrons inevitably engages in as soon as they are next to each other on the same rung. Despite all the drive they show for pairing up, as soon as they do, they want to avoid each other.
A radical solution to this problem may be to use chemical radicals. The name is fitting, as these were always thought to be too unstable and uncontrollable for use in such delicate devices. Their advantage lies in the fact that the pairing quarrels are avoided – in a radical, one of the electrons happily takes up the whole rung for itself alone.
My project builds on preliminary work done in the Optoelectronics Group, which showed that it is possible to design a radical molecule in a way that puts its lonely electron not on the topmost rung of the ladder, but buried lower down. This is extremely unusual, and while at first glance it seems this would make the ladder unstable and prone to toppling, it actually makes the structure stunningly robust for use in diodes.
In my work I am developing new ultrafast optical experiments that shine light on the mechanistic details of the operation of such systems, as well as working on their theoretical description. We will also deploy these materials in new spintronic devices in collaboration with the Hofmann Group. It’s amazing to think that the family of materials responsible for the catastrophic ozone hole above the Antarctic may now be used for revolutionising green technologies. Hopefully these radicals will soon be tamed to benefit all of society.