A study on interfacial microstructure function in organic light emitting diodes (OLED) was performed. A spincoated, hole injecting tetraaryldiamine TPD-Si2 layer was shown to increase maximum OLED luminance and quantum efficiency. Devices with a TPD-Si2 anode adhesion layer provided a maximum luminance level of 15,000 cd m-2 in the absence of dopants or low work function cathodes. It was shown that copper phthalocyanine interlayers nucleated TPD crystallization on heating above the glass transition temperature of TPD
