RGB optimization in a top-emission organic light-emitting device

In this paper, we demonstrate simulation results of top-emission organic light-emitting devices (TOLEDs) with red, green and blue (RGB) colors. We take the RGB spectral peaks at 460, 520, and 600 nm with full width at half maximum of 100 nm. Device structures are thick silver (Ag) anode /hole-transport layer 60 nm/ emitting layer (EML) /semi-transparent Ag cathode 20 nm/ dielectric layer. The dielectric material capped upon the cathode is zinc selenium with a refractive index of 2.6 for providing high output intensity and narrow FWHM. When monitoring the peak wavelengths of RGB device and varying the EML and dielectric thicknesses, we found the optimized value of the EML are 71, 47 and 31 nm for the red, green and blue devices, respectively. The optimized dielectric thicknesses are 80, 70 and 50 nm with periods of 117, 98 and 90 nm, respectively, for the RGB devices. Due to the limitations of the experiments, the EML thicknesses can be different and the dielectric thickness must be the same of the RGB devices. For optimizing the BGB devices simultaneously, the thickness of dielectric layer of the OLED is 667 nm. The RGB peak intensities are 0.96, 0.99 and 0.83, normalized to their optimized value. Typically, in a TOLED, green device exhibits higher efficiency than red and blue ones. That means the intensity of the green TOLED can be lower. When the dielectric layer thickness is 314 nm, the normalized RGB peak intensities are 0.99, 0.26 and 0.97.