两种聚对苯乙炔类衍生物的线性与非线性光学性质

采用吸收光谱、荧光光谱和皮秒Z-扫描等实验方法研究了侧链长度的不同对聚2-甲氧基-5-(2′-乙基-己氧基)]对苯乙炔(MEH-PPV)和聚(2,5-二辛氧基)对苯乙炔(DO-PPV)两种聚对苯乙炔(PPV)衍生物光学性质的影响,并用π-电子共轭结构理论和共振、非共振增强理论进行了分析。结果表明,侧链较长的MEH-PPV的吸收峰和荧光发射峰比DO-PPV相应的吸收和荧光峰均有所红移;侧链结构及共振增强使得MEH-PPV的三阶非线性极化率比DO-PPV增强了近两个量级,并在532 nm激发时,χ(3)具有最大值9.30×10-10esu。

Linear and Nonlinear Optical Properties of Two PPV Derivatives

The effect of side chains with different length on the optical properties of two PPV derivatives, poly (2,5-dioctyloxy-1,4-phenylenevinylene) and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene), was investigated by absorption spectroscopy, fluorescence spectroscopy and picosecond Z-scan technique. The optical properties of two derivatives were discussed using the theories of π-electron conjugated structure and resonant/non-resonant enhancement, respectively. The obtained results demonstrated that the absorption and fluorescence emission bands of MEH-PPV shift towards the long wavelength direction compared with the counterparts of DO-PPV. Furthermore, the side chains also affect the third-order nonlinear susceptibilities χ(3) of PPV polymers. Under the resonant excitation, the third-order nonlinear susceptibility χ(3) of MEH-PPV at 532 nm is two orders of magnitude larger than that of DO-PPV, and reached a maximum of 9.30×1010 esu.