Enhancement of optical properties of poly (9,9'-di-n-octylfluorenyl-2,7-diyl) in conjugated polymer/Ti[O.sub.2] nanocomposites

The influence of colloidal Ti[O.sub.2] nanoparticle contents on the optical properties of poly (9,9'-di-n- octylfluorenyl-2,7-diyl) conjugated polymer (PFO) has been investigated. The solution blending method was used to prepare homogenous PFO/Ti[O.sub.2] nanocomposite. The nanocomposite films were prepared on glass substrates using the spin-coating technique. The films were divided into two groups, the first was left to dry at room temperature while the second was heat-treated at 120°C for 1 h. Absorption and emission spectra showed that the PFO existed in α- and β-phases morphology having monomeric, excimeric, and double excimeric states. In addition, both spectra revealed that Ti[O.sub.2] contents and heat treatment temperature extended the conjugation length of PFO. Finally, emission spectra for both cases exhibited decreasing in the line width of zero- phonon emission spectra and increasing in the vibronic splitting energy, upon increment of the Ti[O.sub.2], led to a significant increase in π-electron delocalization and lower degree in chain disorder. PACS No.: 78.66. Nous etudions l'influence du contenu colloidal de nanoparticules de Ti[O.sub.2] sur les proprietes optiques du polymere conjugue poly(9,9-di-n-octyl fluorenyl-2 7-diyl) (PFO). Nous utilisons le melange de solutions pour preparer du PFO/Ti[O.sub.2] composite homogene. Les films de nano-composites sont prepares sur des substrats de verre par enduction centrifuge. Les films sont divises en deux groupes, le premier est laisse a secher a la temperature de la piece, alors que le second est traite a 120°C pendant une heure. Les spectres d'emission et d'absorption montrent que le PFO existe dans une morphologie de phase α et de phase β, ayant des etats de type monomere, excimere et double excimere. De plus, les spectres dans les deux cas revelent que le contenu en Ti[O.sub.2] et le traitement en temperature etendent la longueur de conjugaison du PFO. Finalement, les spectres d'emission dans les deux cas, montrent une diminution de la largeur de raie des spectres d'emission sans phonon et une augmentation de l'energie de separation vibronique, sous augmentation de Ti[O.sub.2], menant a une augmentation significative de la delocalisation de l'electron π et a un plus bas degre du desordre de chaine. [Traduit par la Redaction]
1. Introduction Conventionally, polymeric materials are filled with synthetic or natural inorganic compounds to improve their optoelectronic properties. Therefore the final optoelectronic properties of the nanocomposites depend on the properties [...]