title: The role of triphenylamine in the stabilization of highly efficient polyfluorene-based OLEDs: a model oligomers study.
abstract: In order to understand the factors responsible for the improved efficiency and stability of organic light-emitting diodes (OLEDs) based on poly(9,9-dioctylfluorene) (PFO) when triphenylamine (TPA) is introduced as lateral fluorene substituent, we synthetize mono-disperse fluorene-thiophene oligomers as model compounds. Their blends with different concentrations of the fluorenone containing oligomer are studied in order to verify if only a reduction of ketonic defect sites or also an impeded energy transfer (ET) towards such sites are responsible for the suppression of the green emission band. We show that the introduction of TPA groups leads specifically both to an antioxidant action and a reduced ET towards residual defect sites, thanks to the environmental micro-encapsulation role played by TPA units surrounding the polymer backbone. As a result, the performances and colour stability of a device fabricated with TPA-substituted PFO (PFTPA) are strongly improved with respect to standard PFO device prepared in the same conditions.
authors: Istituto per lo Studio delle Macromolecole, CNR, Via Bassini 15, 20133 Milano, Italy. m.pasini@ismac.cnr.it
authors: Mariacecilia
authors: M
authors: Pasini
authors: Umberto
authors: U
authors: Giovanella
authors: Paolo
authors: P
authors: Betti
authors: Alberto
authors: A
authors: Bolognesi
authors: Chiara
authors: C
authors: Botta
authors: Silvia
authors: S
authors: Destri
authors: William
authors: W
authors: Porzio
authors: Barbara
authors: B
authors: Vercelli
authors: Gianni
authors: G
authors: Zotti