Ultra-low voltage organic light-emitting diodes based on PiN structures

We demonstrate an efficient organic electroluminescent devices with p-i-n structure. Anamorphous starburst, 4,4',4"-tris(3-methylphenylphenylamino)triphenylamine doped with a strong organic acceptor, tetrafluoro-tetracyanoquinodimethane serves as the p-type hole transport layer, and 4,7-diphenyl-1,10-phenanthroline doped with Li as the n-type electron transport layer. A breakthrough is achived in the performances of device based on pure 8-trishydroxyquinoline as an emitter: 100 cd/m(2) at 2.52V, 1,000cd/m(2) at 2.9V and the maximum luminance and efficiency reache 66, 000cd/m(2) and 5.25 cd/A, respectively. The efficiency can be kept above 3 cd/A in a very large luminance region from 100 to 55,000 cd/m(2).