Photoluminescence properties of vacuum-deposited organic molecule-oxide (MePTCDI-SiO2) mixed layers

Thin films of the perylene derivative N,N′-dimethylperylene-3,4,9,10-bis-dicarboximide (MePTCDI) incorporated in SiO₂ matrix at various concentrations are obtained by condensation of host and dye in high vacuum. Photoluminescence spectroscopy is applied to study the spectral properties of the layers. Significant alterations in luminescence spectra in dependence on dye quantity are explained as a consequence of dye aggregation and resonant energy transfer. We demonstrate that the deposition geometry and preparation conditions offer an effective way to reduce the possibilities for non-radiative transitions, thus increasing the photoluminescence quantum efficiency.