Conductive and optical properties of PPV modified by N+ ion implantation

Abstract

In this article, a soluble poly[2-methoxy-5-(3′-methyl)butoxy]-p-phenylene vinylene (MMB-PPV) was synthesized by dehydrochlorination reaction and the MMB-PPV film was implanted by nitrogen ions (N+) with the ion dose and energy in the range of 3.8 × 1015 to 9.6 × 1016 ions/cm2 and 15–35 keV, respectively. The surface conductivity, optical absorption, optical band gap (Eg) of modified MMB-PPV film were studied, and the third-order nonlinear optical susceptibility (χ(3)) as well as its environmental stability of modified MMB-PPV film were also measured by degenerate four-wave mixing system. The results showed that the surface conductivity of MMB-PPV film was up to 3.2 × 10−2 S when ion implantation was performed with the energy of 35 keV at an ion dose of 9.6 × 1016 ions/cm2, which was seven order of magnitude higher than that of the pristine film. UV-Vis absorption spectra demonstrated that the optical absorption of MMB-PPV film was enhanced gradually in the visible region followed by a red shift of optical absorption threshold and the Eg value was reduced from 2.12 eV to 1.59 eV with the increase of ion dose and energy. The maximum χ(3) value of 2.45 × 10−8 esu for modified MMB-PPV film was obtained with the ion energy of 20 keV at an ion dose of 3.8 × 1016 ions/cm2, which was almost 33 times larger than that for pristine film. In comparison to the reduction of 17% in the χ(3) value of pristine MMB-PPV film, the maximum χ(3) value of 2.45 × 10−8 esu for modified MMB-PPV film decreased by over 5.3% when they had been exposed under the same ambient conditions for 90 days. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 2072–2077, 2010