Abstract
We demonstrate at a very high luminance an extraordinary high-efficiency red fluorescent organic light emitting diode (OLED) by using a novel red emitter, 3-(N,N-diphenylamino)-7-di(cyanoyl)-5,5 -spirofluorenyl-5H-dibenzo [a,d] cycloheptene (N-STIF-DCN).The device exhibits, at 33,000 cd/m2 for example, a major peak at 612 nm with an external quantum efficiency of 8.5% with 13.6 cd/A and 3.0 lm/W, The high efficiency oberserved at the extremely high brightness may be attributed to four efficiency-effective architectural factors of the device designed as well as the unique electro-luminance effective material factor of the red dye synthesized. The five efficiency-effective architectural factors are low injection barrier, balanced carrier injection, effective carrier confinement, maximum excitons generation in both host and guest, and effective host-to-guest energy transfer.