Influence of SiO₂/TiO₂ Nanocomposite on the Optoelectronic Properties of PFO/MEH-PPV-Based OLED Devices

The influence of SiO₂/TiO₂ nanocomposites on the performance of organic light-emitting diodes (OLEDs) based on poly(9,9'-di-n-octylfluorenyl-2,7-diyl) (PFO) and various amounts of poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) was investigated. Prior to the fabrication of the OLEDs on indium-tin oxide (ITO) substrates, the hybrids of PFO/MEH-PPV, in the presence and absence of the SiO₂/TiO₂ nanocomposites, were prepared via the solution blending technique. Improvement of the performances of the devices in the presence of the SiO₂/TiO₂ nanocomposites was detected. The existence of the SiO₂/TiO₂ nanocomposites led to better charge carrier injection and, thus, a significant reduction in the turn-on voltage of the devices. The enhancement of MEH-PPV electroluminescence peaks in the hybrids in the presence of SiO₂/TiO₂ nanocomposites is not only a result of the Förster resonance energy transfer, but also of hole-electron recombination, which is of greater significance. Moreover, the existence of the SiO₂/TiO₂ nanocomposites led to a shift of the CIE chromaticity coordinates of the devices.