[Spectrum study on highly saturated blue organic top-emitting devices with microcavity structure].

The blue top-emitting organic light-emitting devices with cavity effect have been fabricated. The authors used the TBADN : 3% DSAPh as emitting material of blue microcavity OLEDs. The devices consisted of Ag/ITO/CuPc/NPB/TBADN : 3% DSAPh/Alq3/LiF/Al(Ag) structure. On a patterned glass substrate, silver was deposited as reflective anode, and copper phthalocyanine (CuPc) layer as HIL and 4'-bis[N-(1-Naphthyl)-N-phenyl-amino] biphenyl (NPB) layer as HTL were made. Aluminum and silver thin films were made as semi-transparent cathode. The transmittance of aluminum and silver (Al/Ag) cathode was about 30%. In EL spectrum, the full width at half maximum (FWHM) was only 17 nm. By changing the thicknesses of ITO, highly saturated color with Commission Internationale de L'Eclairage chromaticity coordinates (CIEx,y) of (0.141, 0.049) was obtained. In the present article, the emission intensity of spectrum was studied. An appropriate cathode transmittance will result in maximal emission intensity. By using the formula of microcavity, the approximative curve that describes the change of emission intensity with cathode transmittance (or reflectance) was figured out.