Colour tunability of blue top-emitting organic light-emitting devices with single-mode resonance and improved performance by using C60capping layer and dual emission layer

p-di(p-N,N-diphenyl-amino-styryl)benzene (DSA-Ph)-based blue top-emitting organic light-emitting devices (TOLEDs) with low bias and single-mode resonant emission were fabricated. Microcavity optimization was demonstrated by altering the hole-transport-layer thickness. C60 was demonstrated to be an effective capping layer and improved the luminance by a factor of 1.6 in between the maximum and minimum transmittance of top contact. For sky-blue TOLED, the luminance was enhanced by 50% by using a dual emission layer composed of DSA-Ph doped 2-(t-butyl)-9,10-di(2-naphthyl)anthracene and DSA-Ph doped tris(8-hydroquinoline) aluminium (Alq3). The improvement was attributed to the energy transfer from Alq3 to DSA-Ph and DSA-Ph directly harvesting carriers in the emission layer of Alq3 : DSA-Ph.