Effect of SiO2/Si3N4 dielectric distributed Bragg reflectors (DDBRs) for Alq3/NPB thin-film resonant cavity organic light emitting diodes

In this article, we report on the effect of SiO2/Si3N4 dielectric distributed Bragg reflectors (DDBRs) for Alq3/NPB thin-film resonant cavity organic light emitting diode (RCOLED) in increasing the light output intensity and reducing the linewidth of spontaneous emission spectrum. The optimum DDBR number is found as 3 pairs. The device performance will be bad by further increasing or decreasing the number of DDBR. As compared to the conventional Alq3/NPB thin-film organic light emitting diode (OLED), the Alq3/NPB thin-film RCOLED with 3-pair DDBRs has the superior electrical and optical characteristics including a forward voltage of 6 V, a current efficiency of 3.4 cd/A, a luminance of 2715 cd/m2 under the injection current density of 1000 A/m2, and a full width at half maximum (FWHM) of 12 nm for emission spectrum over the 5–9 V bias range. These results represent that the Alq3/NPB thin-film OLED with DDBRs shows a potential as the light source for plastic optical fiber (POF) communication system.