共轭聚合物MDMO-PPV的压阻效应研究

The Investigation of Piezoresistance of MDMO-PPV

本文使用纳米压痕技术测试了聚[2-甲氧基-5-(3′,7′-二甲基辛氧基)-1,4-苯乙炔](MDMO-PPV)的机械性能,发现MDMO-PPV薄膜的杨氏模量与测试时的最大载荷相关.当载荷撤去后,在薄膜上有一个可以通过预压除去的残余形变.预压处理后,薄膜表现出良好的弹性.我们还制备了ITO\MDMO-PPV(80nm)\Al(75nm)结构的压阻器件,测试了在不同压力下的J-V特性曲线.在电压小于1V时,器件的电流传输机制在不同外加压力下均呈现欧姆定律机制;而在电压2~5V范围内,随外加压力增大,电流传输呈现陷阱电荷传输机制(TCLC)和欧姆定律机制共同作用,并逐渐转变为欧姆定律机制.器件在工作电压为1.5V时压阻系数最大,达到3.92×10-2 Pa-1.最后我们对外加压力如何影响器件电流的传输提出了一种可能的机理解释.

The mechanical properties of Poly E 2-methoxy-5-（ 3＇, 7＇-dimethyloctyloxy）-l, 4-phenylenevinylene] （MDMO-PPV） were measured using nanoindentation. It is found that the Young＇s Modulus of MDMO-PPV was affected by the maximum loading force. A residual deformation remained when the first loading force was unloaded, and it could be eliminated by preloading process. After preloading process, the film exhibited a good elasticity. The devices with structure of ITO／MDMO-PPV （80 nm）／A1 （75 nm） were fabricated and their J-V characteristics were measured under different stresses. When the voltage was less than 1 V, the J-V characteristics of the device are consistent with the Ohm＇s law under all stresses; when the voltage ranged from 2 to 5 V, the device exhibits different conductive mechanisms, changing from the trapped charge limited current （TCLC） mechanism to Ohm＇s law when the stresses increased. The device showed the highest piezoresistanee coefficient when the working voltage was 1.5 V, reaching a. 92 ×10^-2 Pa^-1. An explanation was proposed for explaining the change on conductive mechanism induced by the stress.