Influences of resonant wavelengths on performances of microcavity organic light-emitting devices

In this letter, we investigate theoretically and experimentally the influences of resonant wavelengths on performances of microcavity organic light-emitting devices. Results show that by setting the normal-direction resonant wavelength around the peak wavelength of the intrinsic emission, one obtains the highest luminance enhancement along the normal direction and hardly detectable color shift with viewing angles, yet accompanied by highly directed emission. On the other hand, the highest enhancement (∼1.4 times) in external quantum efficiencies and the most uniform brightness distribution are obtained by setting the normal-direction resonant wavelength of 20–40nm longer than the peak wavelength of the intrinsic emission, yet with noticeable color shift over viewing angles. Due to the trade-offs between different emission characteristics in choosing the resonant wavelength, the exact design of microcavity devices would depend on actual applications.