Scientists at Princeton University in New Jersey have developed a class of metal-free cathodes for use in organic light-emitting diodes (LEDs) along with phototransistors, photodetectors, solar cells and lasers.
Typically, organic LEDs employ a more reflective and absorptive cathode containing a thin film of magnesium and silver capped with indium tin oxide. The metal-free cathode employs a thin film of copper phthalocyanine, also capped with indium tin oxide. Because of the low reflectivity, this new type of LED has an 85 percent transmission rate in the visible and emits nearly identical amounts of light in both the forward and backscattered directions.