Abstract
Horizontally oriented ter (9, 9’-spirobifluorene) (TSBF) based organic light-emitting diodes (OLEDs)
were fabricated with the device structure that has no heterointerfaces (anode/n-TSBF/TSBF/p-TSBF/
cathode). Optimizing the doping concentration and the thicknesses of n-and p-doped TSBF layers, we
found the possibility to suppress the efficiency roll-off characteristics. These results indicate the
potential use of TSBF for realizing organic solid-state lasers.