Researchers from Umeå University, Linköping University, and Swedish company LunaLEC AB have developed light-emitting electrochemical cells (LECs) that emit strong light at high efficiency. Using a systematic combination of experiments and simulations, researchers established a generic set of design principles, including balanced trap depths, optimized doping and electrochemically stable materials. The researchers' approach has paved the way for LEC devices that emit light with a high brightness of 2000 cd/m2 at an electron-to-photon efficiency of 27.5 percent. "As a point of reference, a normal TV operates between 300 to 500 cd/m2, while 2000 cd/m2 is the typical brightness of an OLED illumination panel,” said professor Ludvig Edman of Umeå University. “Concerning efficiency, our LEC device is close to that of common fluorescent tubes.” Researchers created LECs that are thin, flexible, lightweight and can be driven to essentially any emission color by the low voltage of a battery. Researchers say their development can be fabricated with low-cost printing and coating methods. "With this performance, the LEC component is now not only offering low costs and highly attractive design advantages, but is also becoming a true competitor with existing technologies, such as the fluorescent tube, LED and OLED, regarding efficient and practical operation," said professor Martijn Kemerink of Linköping University. The thin, flexible and lightweight LEC could improve applications within home diagnostics, signage, illumination and health care. The research has been published in Nature Communications (doi:10.1038/s41467-017-01339-0).