Researchers from Shanghai University, Jiangsu University of Science and Technology, Chinese Academy of Sciences, Tongji University, Jilin University, Southern University of Science and Technology, University of Nottingham and Okinawa Institute of Science and Technology have developed efficient and stable perovskite light-emitting diodes (PeLEDs) with saturated blue emission, by building hydrogen-bonding networks both inside the perovskite layer and at its interface using a pair of isomeric molecules. Over the past decade PeLEDs have grown brighter and cheaper to make, and compositional tuning has taken them across the visible spectrum, with red and green devices now matching - and in places beating - rival LED materials. Blue electroluminescence, however, has lagged badly behind, and that gap alone has kept full-color perovskite displays out of reach. The reason is structural - blue emission requires a wider bandgap, which in turn demands a higher operating voltage from the device. In a material held together by ionic bonds, that extra electrical stress aggravates the instability of the perovskite's octahedral framework, and the lattice degrades quickly. The result, until now, has been blue devices that are both dimmer and shorter-lived than their red and green counterparts.
Isomeric hydrogen-bonding networks push blue perovskite LEDs to 22% EQE
