Red organic light emitting device with improved performance using a novel fluorescent dye codoped with phosphor-sensitizer

Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-(dicyanomethylene)-5,5-dimethyl-1-(4-dimethylamino-styryl) cyclohexene (DCDDC), and a green phosphorescent dye, fac tris(2-phenylpyridine) iridium [Ir(ppy)3] were codoped into a host material 4,4'-N,N'-dicarbazolebiphe-nyl (CBP). By adjusting the component ratio of doping system, a series of devices with different concentration proportion of Ir(ppy)3:DCDDC were constructed. The results demonstrated that the device with 0.2 wt% DCDDC had a maximum power effi-ciency (ηp) of 2.12 lm/W at a current density of 0.1 mA/cm2, which was about 38% higher than that of conventional fluorescent device. When at a current density of 4 mA/cm2 (100 cd/m2) and 52 mA/cm2 (1000 cd/m2), the ηp percentage was about 160% and 143% higher than that of conventional device, respectively. A stable red light emission at a peak of 615 nm with Commissions Internationale de l'Eclairage coordinates near the region of (0.56, 0.42) in a wide bias range was also obtained. The improved performances were attributed to the efficient multiple-stage energy transfer from the host to the guest and the suppression of loss mechanism.

Efficient red organic light-emitting device consisted of a compound fluorescent-phosphor-sensitized emission layer was fabricated. A novel red fluorescent dye, 3-（dicyanomethylene）-5,5-dimethyl-1-（4-dimethylamino-styryl） cyclohexene （DCDDC）, and a green phosphorescent dye, fac tris（2-phenylpyridine） iridium [Ir（ppy）3] were codoped into a host material 4,4＇-N,N＇-dicarbazotebiphenyl （CBP）. By adjusting the component ratio of doping system, a series of devices with different concentration proportion of Ir（ppy）3：DCDDC were constructed. The results demonstrated that the device with 0.2 wt% DCDDC had a maximum power efficiency （ηp） of 2.12 lm/W at a current density of 0.1 mA/cm^2, which was about 38% higher than that of conventional fluorescent device. When at a current density of 4 mA/cm^2 （100 cd/m^2） and 52 mA/cm^2 （1000 cd/m^2）, the r/p percentage was about 160% and 143% higher than that of conventional device, respectively. A stable red light emission at a peak of 615 nm with Commissions Internationale de l＇Eclalrage coordinates near the region of （0.56, 0.42） in a wide bias range was also obtained. The improved performances were attributed to the efficient multiple-stage energy transfer from the host to the guest and the suppression of loss mechanism.