Time resolved emission spectroscopy of poly(2,5-dicyano-p-phenylene-vinylene) films

Journal of the Brazilian Chemical Society

Jarem R. Garcia¹  Marcelo H. Gehlen¹  Hueder P. M. De Oliveira¹  Francisco C. Nart¹ 

[1] ,Universidade de São Paulo Instituto de Química de São Carlos São Carlos SP ,Brazil

关键词: conjugated polymer;    PPV;    excited-state dynamics;    fluorescence decay;   

DOI  :  10.1590/S0103-50532008000700012

来源: SciELO

【 摘 要 】

Films of poly (2,5-dicyano-p-phenylene vinylene), DCNPPV, were obtained by electrochemical synthesis over gold thin layer (20 nm) transparent electrode deposited on a glass plate. The DCNPPV films of 4 µm thickness were produced by electropolymerization process of α,α,α',α'-tetrabromo-2-5-dicyano-p-xilene at different applied potentials (-0.15, -0.25, -0.40, -0.60, -0.80, and -1.0 V) using 0.1 mol L-1 of tetraethylammonium bromide in acetonitrile as the supporting electrolyte. The emission decays have three exponential components: a fast component in the picosecond range (200-400 ps), and two other of about one and five nanoseconds at 293 K. The fluorescence quenching process seems to occur by exciton trapping in a low-energy site and quenching by residual bromine monomer attached at the end of the polymer chain. However, the electrochemical synthesis generates entrapped bromide or ion pairs during the growth step of the film which also contributes to the deactivation. The change of the electrolyte from bromide to perchlorate reduces significantly this additional quenching effect by allowing ion exchange of formed bromide with the nonquenching perchloride anion.

【 授权许可】

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