Study On Photoluminescence Of Conjugated Polymer (PFO)/Inorganic Particles Nanocomposites

Conjugated polymers have been intensively studied during the last two decades mainly due to their semiconductor-like optical and electronic properties. These organic materials have the capability to be processed on a variety of substrates as well as to allow a broad tunability of emission by controlling their chemical structure.There is strong dependence of optical properties of conjugated polymers on chain conformation, which opens room for the use of nanoscale architecture to control the polymer conformation. In particular, isolation of conjugated chains within inorganic materials plays an important role in improving optical and electronic properties of conjugated polymer due to the novel synergy effects.Among porous SiO₂, spheric SiO₂, TiO₂ , unmodified A1₂O₃ , modified Al₂O₃, two suitable nanoparticles were selected to incorporate with conjugated polymer (poly (9,9-dioctylfluorene), PFO). One of them is modified Al₂O₃, due to its excellent dispersion in organic solvent like CHCl₃, to fabricate PFO/Al₂O₃ nanocomposite; the other is porous TiO₂, due to its nanopores in TiO₂ crystalline film, to fabricate PFO/TiO₂ nanocomposite. Optical properties of both nanocomposites were investigated in detail.Nanocomposite film of PFO/Al₂O₃ has been prepared by blendingthe conjugated polymer solution with alumina nanoparticle dispersion in common organic solvent, investigated in terms of the optical properties. A blue shift of the photoluminescence (PL) spectrum for the fabricated PFO/AI2O3 nanocomposite film was observed as compared to the results obtained from the bulk PFO film, the maximum of the PL emission peaks occured at 442 nm in the bulk film while after the incorporation of the alumina nanoparticles the maximum appeared at 420 nm in the spectrum for PFO/AI2O3 nanocomposite film; the dependence of fluorescence blue shift of PFO on the concentration of AI2O3 was investigated; and the excimer formation that led to long wavelength tails was found to reduce in PFO/AI2O3 nanocomposite. All these results provide rich information for the conclusion that the isolation of the conjugated polymer chains by the flat rafts of alumina nanoparticles plays a key role for the obtained blue shift.PFO/T1O2 complex nanomaterial was successfully prepared through the adsorbing of polymer on the surface of nanocrystalline TiO2 film. The photoluminescence (PL) spectrum of the obtained nanocomposite showed 28 nm of red-shift, as compared to the bulk polymer film. The maximum of the PL emission peaks of the pure bulk polymer occured at 442 nm, while the maximal emission for nanocomposite film appeared at 470 nm. The adsorption of the conjugated polymer chains on the nanopores of TiC>2 film played a key role for the obtained red shift. Theobservation of phenomenon in PFO/TiO2 composite brought about the significant potential for modifying the optical emission properties of conjugated polymer by adsorption the polymer chains within inorganic nanostructure materials.Different inorganic particle has diverse effect on the emission of conjugated polymers. Controlling the chemical structure of polymer chains by the use of nanoscale architecture can be a fundamental solution to obtain the novel optical properties of conjugated polymers...