Control of emission characteristics in organic thin-film electroluminescent diodes using an optical-microcavity structure

An electroluminescent diode with a microcavity structure which comprised a reflective Ag anode (36 nm), a hole transport dye layer (250 nm), an emission dye laser (15 nm), an electron transport dye layer (240 nm), and a reflective MgAg cathode was fabricated. A diode without the microcavity structure with a transparent ITO anode was also prepared for reference. The diode with microcavity was driven in the electric excitation mode and emission spectra at fixed detection angles were measured together with the angular dependence of emission intensity at fixed wavelengths. A sharpening of emission spectra and a marked alteration of emission patterns in the diode with microcavity were observed.