Synthesis and optical properties of organic semiconductor: zirconia nanocomposites

Oxide nanoparticles were used as carrier for organic semiconductor materials. Stable suspensions of ZrO2 nanoparticles coated with anthracene, pentacene, or para-hexaphenyl were obtained by microwave plasma synthesis of ZrO2 cores, subsequent in situ coating with organic compounds, and in situ dispersion in ethylene glycol. Powders of coated oxide nanoparticles were synthesized for comparison. The successful coating and a small uniform size distribution of the ZrO2 cores were confirmed by comprehensive characterization including photoluminescence, absorption spectroscopy, electron microscopy, electron energy loss spectroscopy, mass spectrometry, and X-ray diffraction. Powder compacts of anthracene-coated ZrO2 particles showed good air stability and a significant blue shift accompanied by an attenuation of the emission lines at higher vibronic orders in comparison to samples of pure anthracene as received. For para-hexaphenyl-coated nanoparticles, the same photoluminescence characteristics are observed as for pure para-hexaphenyl. In the case of pentacene-coated nanoparticles indication for degradation is found.