Showing papers by "Bo Peng published in 2008"

Synthesis and Characterization of Pyrene‐Centered Starburst Oligofluorenes

Abstract: A series of starburst materials (T1-T3) based on a pyrene core with four oligofluorene arms of different length have been synthesized and characterized. The starburst materials show good film forming ability and sky blue fluorescence. Electroluminescent devices take on a stable blue emission and the device performance increases with an increase in arm length. The single-layered device made of T3 has a maximum brightness of over 2700 cd.m 2 and a maximum current efficiency of 1.75 cd .A -1 , which is among the best in starburst material devices. The morphology of T1-T3 has been studied by atomic force microscopy. The starburst oligofluorenes with different arm lengths show a distinctive texture, which indicates the size dependent morphology of the starburst materials.

Synthesis and characterization of poly(fluorene vinylene) copolymers containing thienylene–vinylene units

Abstract: Narrow-band-gap 2,5-thienylene-divinylene (ThV) units were incorporated into the poly(fluorene vinylene) backbone via a Gilch reaction as an energy trap with various feed ratios; this yielded pronounced changes in the electrochemical and optical properties of the material. The energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the polymers {poly(9,9-di-iso-octylfluorene vinylene) [poly(fluorene vinylene-co-thiophene vinylene (FV))], C1, and C2} were estimated to be −5.53 to −5.10 eV and −2.98 to −2.84 eV, respectively, by cyclic voltammetry measurements. In comparison with poly(FV), the HOMO energy levels of polymers poly(fluorene vinylene-co-thiophene vinylene (FV) (90 : 10) (C1) and poly(fluorene vinylene-co-thiophene vinylene (FV) (80 : 20) (C2) were significantly increased, but their LUMO energy levels were slightly decreased. The optical properties were investigated by absorption and emission spectra of the polymers. The good spectral overlap between the emission of poly(FV) and the absorption of polymers C1 and C2 revealed a sufficient energy transfer from the majority of 9,9-di-iso-octylfluorene vinylene units to the minority of ThV units. The reduction of self-absorption losses of polymers C1 and C2 due to spectral separation caused by the incorporation of ThV units could be indirectly confirmed by nonlinear optical (NLO) properties. The result of the NLO properties of the polymers showed that the third-order NLO coefficients of poly(FV), C1, and C2 were 8.1 × 10−10, 1.35 × 10−9, and 1.51 × 10−9 esu, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Synthesis and Characterization of Novel Monodisperse Starburst Oligo(fluoreneethynylene) Based on Truxene Moiety

Abstract: A series of novel monodisperse star-shaped oligo(fluoreneethynylene)s, which contain hexahexyltruxene as the central core linked with oligo(fluoreneethynylene) as the arms, are presented.

Synthesis and optoelectronic characterization of poly(fluorenylethynylene)s containing perylene bisimide moiety in the backbone

Abstract: A series of poly(fluorenylethynylene)s containing different ratios of perylene bisimide moiety in the backbone were synthesized by Sonogashira cross-coupling reaction. The electron-deficient perylene bisimide moiety was introduced into the backbone to construct the donor-acceptor architectures. The chemical structures of these copolymers were determined by 1 H NMR and FTIR. The solubility, thermal, and optoelectronic properties were studied. The results of UV-vis absorption and fluorescence spectra of these copolymers showed that intramolecular energy transfer and charge separation occur between the fluorenyl alkyne segment and perylene bisimide moiety.