Researchers have demonstrated the OLEDs could be used to make organic lasers. As described in a paper published this week in Applied Physics Letters, OLEDs made with finely patterned structures can produce bright, low-power light sources, a key step in making electrically-driven organic lasers.
Organic light emitting diodes (OLEDs) will represent a global market of almost $170 million in 2020, according to market analyst Yole. They are flexible, thin, ultra-light, and more energy-efficient than LCDs.
OLEDs operate through the interaction of electrons and holes. In the new study, carried out by researchers from the University of California and Kyushi University in Japan, OLEDs were produced with efficiencies almost two orders of magnitude higher than current devices.
Researchers have have been hindered in building organic lasers by the organic materials' tendency to operate inefficiently at the high currents required for lasing.
Production of OLED-based lasers requires current densities of thousands of amperes per square centimetre, but until now current densities have been limited by heating. ‘At high current densities, brightness is limited by annihilation processes,’ commented co-author of the Applied Physics Letters paper, Chihaya Adachi of Kyushu University.
In previous work, Adachi and colleagues showed OLED performance at current densities more than 1kA/cm2 but without the necessary efficiency required for lasers and bright lighting.
In their current paper, they show that the efficiency problem can be solved by using electron-beam lithography to produce finely-patterned OLED structures. The small device area supports charge density injection of 2.8 kA/cm2 while maintaining 100 times higher luminescent efficiency than previously observed.