Organic Molecules That Glow At Room Temperature Make Energy-Efficient Lights
As efficient as light emitting diodes (LEDs) have made lighting, there is plenty of potential for further improvement. Even highly efficient LED lights waste a lot of the electricity they consume as heat. The quest to produce still more light using less energy has been caught between two classes of molecules, each with different drawbacks. The easiest phosphorescent molecules to make rely on metals that would be expensive, and often toxic, if used widely. Organic versions work best at impractically low temperatures, and have to be protected from oxygen. So Professor Ben Zhong Tang’s announcement of the creation of a class of room-temperature phosphorescent (RTP) organic molecules could be a game-changer. His team of chemists has produced a set of organic molecules that glow at room temperature and consume very little energy to do so. They even come in a range of attractive colours, although pretty lights represent a small fraction of their potential. Tang and his graduate students at the Hong Kong University of Science and Technology started by considering what organic molecules might light up at room temperature, modelled the structures required for best performance based on the energy levels of electron orbitals, and then set out to make them. They were able to produce five aromatic molecules that emit light after they have been excited. The longest of these lasts for 230 milliseconds, less than a quarter of a second, after excitation ceases. Short as this sounds, it is a huge increase on many past efforts.
IFL Science, 14 October 2016 ;http://www.iflscience.com ;