Polyfluorenes blue emission

The Problem of Pure Blue Emission in Polyfluorenes Excimer and Aggregate Formation or Fluorenone Defects ... 

X. Gong, P.K. Iyer, D. Moses, G.C. Bazan, A.J. Heeger, and S.S. Xiao, Stabilized blue emission from polyfluorene-based light-emitting diodes elimination of fluorenone defects, Adv. Funct. Mater., 13 325-329, 2003. 

D Neher, Polyfluorene homopolymers conjugated liquid-crystalline polymers for bright blue emission and polarized electroluminescence, Macromol. Rapid Common., 22 1365-1385, 2001. 

Wu et al. [31] have recently presented a novel concept of designing oxygen nanosensors. They used the precipitation method to obtain polyfluorene beads (0 25 nm) doped with the oxygen indicator platinum(II) octaethylporphyrin. Poly (9,9-dihexylfluorene) belongs to materials widely used in OLEDs and has a bright blue emission when excited in the UV region. In beads, FRET-mediated red emission... 

Scheme 17 Polyfluorene and typical hole-transporting material blended with it to obtain a stable blue emission...

Dendronised Polyfluorenes - Towards Stable Blue Emission... 

An industrial group have reported obtaining efficient red, green, and blue emission from polyfluorene-based alternating copolymers prepared by Suzuki polycondensation, but without publishing their structures [270,271]. 

Spiro-functionalisation with groups at C9 has also been examined as a means to stabilise blue emission from polyfluorenes. While polymers with spirocycloalkyl groups, e.g. 175 (Scheme 82), display green emission upon annealing [277], the polymer 176 with aryl groups at C9 produces stable blue PL and EL emission even after annealing [278]. 

Polyfluorenes are an important class of LEP with high thermal, photo and environmental stability and efficient bright blue emission. This stimulated a number of researchers to develop fluorene-thiophene copolymers for light-emitting applications. In addition to an expected increase in PL quantum etSciency, such a combination of electron-rich thiophene units with relatively electron-deficient fluorene units should modify the bandgap of the material (and thus tune the emission) and improve the charge injection/transport balance, compared with fluorene homopolymers. 

J. Liu, X. Guo, L. Bn, Z. Xie, Y. Cheng, Y. Geng, L. Wang, X. Jing, F. Wang, White electroluminescence from a single-polymer system with simultaneous two-color emission polyfluorene as blue host and... 

For emission in the blue, disubsdtuted polyfluorene aligned by LC selforganization on pre-oriented substrates gives a polarization ratio of about IS in EL (4). 

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