Impact of fluorinated vinylene units on supramolecular organization and optical properties of poly(p-phenylenedifluorovinylene) thin films as a class of blue band gap conjugated polymers

作者：Losurdo Maria; Giangregorio Maria M; Capezzuto Pio; Bruno Giovanni^*; Babudri Francesco; Cardone Antonio; Martinelli Carmela; Farinola Gianluca M; Naso Francesco; Buechel Michael

来源：Polymer, 2008, 49(19): 4133-4140.

DOI：10.1016/j.polymer.2008.07.024

• MEH-PPDFV
• conjugated polymer thin films
• optical properties

This study is an investigation on the interplay between supramolecular organization and optical properties of thin films of conjugated polymers with fluorinated vinylene units such as poly[2-(2-ethylhexyloxy)-5-methoxyl-1,4-phenylenedifluorovinylene (MEH-PPDFV) and poly(2-methoxy-5-propyloxysulfonatephenylenedifluorovinylene) (MPS-PPDFV), which are both PPV polymers with fluorinated double bonds with alkoxy chains in the 2 and 5 positions. MEH-PPDFV is the fluorinated version of the widely investigated MEH-PPV, and MPS-PPDFV is characterized by the presence of ionic alkoxy side chains. This interplay is elucidated exploiting atomic force microscopy, spectroscopic ellipsometry, and photoluminescence to obtain complementary information. It is demonstrated that the presence of F-atoms in the vinylene units of the MEH-PPDFV yields a blue optical band gap with the maximum of the fundamental HOMO-LUMO transition and of the room temperature photoluminescence at 3.74 eV (331 nm) and at 2.71 eV (458 nm), respectively. The blue-absorption and emission in the thin films are ascribed to the fact that fluorine atoms on the vinylene units prevent pi-stacking of polymeric chains. Furthermore, the dependence of morphology, anisotropy in optical properties and photoluminescence properties of films on deposition methodology is also discussed. MEH-PPDFV also emits homogeneous blue-greenish electroluminescence at 2.46 eV (504 nm).

• 出版日期2008-9-9