Abstract
The effect of TiO2 nanoparticles (NPs) on the energy transfer mechanism from poly(9,9-dioctylfluorene-2,7-diyl) (PFO) to poly(2-methoxy-5(2-ethylhexyl)1,4-phenylenevinylene (MEH-PPV) and to poly 9,9-dioctylfluorene-alt-benzothiadiazole (F8BT), and from F8BT to MEH-PPV was investigated. The binary and ternary nanocomposite thin films were spin-coated on glass substrate after prepared by the solution blending method. The intensity enhancement, the red-shift in the emission spectra and the enhancement in electrical properties, after the NPs added to the ternary blend, confirmed improvements in both the electron-hole recombination and the energy transfer efficiency. To recognize the effect of the NPs on the energy transfer mechanism, the emission and absorption spectra of three nanocomposite binary blends were recorded. The donor and acceptor contents in the blends were kept constant, while the NPs content was varied. Förster radius (Ro) and distance between donor and acceptor molecules (RDA) were calculated and found to be affected by the NPs addition. Successfully, the mechanism of the NPs effect was explained. Several observations indicated that the NPs addition into the blend enhanced the Förster resonance energy transfer (FRET), while obstructed the Dexter energy transfer mechanism. In addition, the measured Commission International d′Eclairage (CIE) coordinates confirmed that the emitted color from the blends can be simply controlled via the NPs addition.