Dr Dan Credgington, Royal Society University Research Fellow at University of Cambridge, researches new ways of making and collecting light. His work looks at turning light into energy using new types of solar panels and turning electricity into light using new types of LEDs and phosphors (materials designed to turn one colour of light into another). As a physicist who has worked at University College London (UCL), Imperial College and Cambridge, Dan is particularly interested in controlling the behaviour of electrons in organic LEDs. In his guest blog post for Inside Science, he explains why you should be interested in light too.

Luminescent inks of quantum dots covering the whole visible spectrum. Credit: Ryan Brady and Tom Jellicoe.

Luminescent inks of quantum dots covering the whole visible spectrum. Credit: Ryan Brady and Tom Jellicoe.

The ability to create light has transformed our lives. The simplest sign of global human activity is a picture of the Earth at night. Our webs of light and hubs of industry trace a glowing network across the planet. Light is essential for a developed society and for economic development, but the way in which we generate it is inefficient and dirty. Even in highly developed nations, tungsten filament lamps (which effectively burn electricity) are only just going the way of gas lights and flaming torches. Their substitutes are expensive and unattractive, pricing poorer communities out of new technologies, while remaining unappealing to those who can afford them. My research seeks to find new ways and new materials to generate light using LEDs, to remove the need for traditional light bulbs and make cheap, efficient lighting accessible for all.

A newly developed ink for converting blue light from an LED into pure white light. Credit: Ryan Brady and Tom Jellicoe.

A newly developed ink for converting blue light from an LED into pure white light. Credit: Ryan Brady and Tom Jellicoe.

Cheap LEDs aren’t just about lighting houses and offices though. Think about the amount of information available at your fingertips through touchscreens and flat-panel displays. This relatively new, and costly, technology has become commonplace, the latest ‘organic’ LED screens are already used in smartphones because the contrast is better and they save power. What if we could build these screens using inkjet or 3D printers? We could make them bigger, cheaper, curved, and maybe flexible. We could put them on windows and windscreens, clothes and furniture. We could print newspapers and posters, postcards and photo books with images which moved and changed. Perhaps ‘print screen’ will have a whole new meaning in a few years? Could you put electronics in a tattoo?

The world's first devices made with a new hybrid printable material, researchers have achieved red and green, and are close to getting blue. Credit: ZK Tan.

The world’s first devices made with a new hybrid printable material, researchers have achieved red and green, and are close to getting blue. Credit: ZK Tan.

These possibilities are half of the reason why I find my research interesting. The other half is the scientific challenge. I’m interested in sustainability and energy: for the first half of my career, my expertise was in materials and devices for making solar panels. A number of years ago, an opportunity came up to study plastic LEDs, but I wasn’t sure if I should go for it as I’d never worked on LEDs before. The physics of LEDs is all about putting charges in, transporting them to where they need to go, and getting them to recombine and release light. The physics of solar panels is all about getting light to where it needs to go, using it to split apart charges, transporting them, and getting them out. At which point it clicked – it turns out the physics, and half of the challenges, are basically the same for both LEDs and solar panels, in fact, one is just the reversal of the other. This means that LED technology constantly informs solar cell technology, and recently the trend has gone back the other way, with new LED materials being found while looking for better solar panels.

I hope this explains a little about the context of my research, and how I ended up doing it. I hope it will also give you food for thought. Perhaps you’ll think of the glowing global network when you switch on a light, or imagine the physics behind the solar lights in your garden, or the LEDs in your smart phone, and where they are taking us to next.

Dan Credgington will discuss the future of light on Earth at our Café Scientifique on 26 May at Royal Society. Click here to register for the event.