Spatial emission patterns in organic thin-film EL diodes

In surface emissive type emissive devices, spatial distribution of emissive patterns is quite important from two viewpoints: First, emissive colors (emission spectra) are highly dependent on the location of emissive sites in thin film EL devices and careful design of device structures is needed for tuning emissive colors. Second, for the evaluations of absolute EL efficiency, the spatial distribution of emissive light are indispensable, although Lambert rule is usually accepted without enough experimental evidence. In this report, we evaluated both spatial distribution of emissive patterns and emission spectra at each emissive direction in the standard type TPD/Alq devices and related two-layer type devices with systematically varied layer thicknesses.