苯并噻二唑基半导体/弹性绝缘体共混柔性薄膜的结构及电荷传输研究

Structure and carrier transport of flexible blend films consisting ofa benzothiadiazole-based semiconducting polymer and an elastomer polymer

利用苯并噻二唑基半导体聚合物PffBT4T-2DT与弹性体聚合物聚二甲基硅氧烷(PDMS)通过溶液相共混,采用旋涂法制备共混薄膜。并采用层压转移法构筑共混薄膜有机场效应晶体管(OFET)来研究薄膜的电荷传输特性随拉伸应变的变化。结果显示,PffBT4T-2DT/PDMS共混薄膜中诱发垂直相分离结构,即PffBT4T-2DT组分富集在薄膜下层而PDMS集中在上层。PDMS引入还导致PffBT4T-2DT骨架链堆垛结构的改变,促使分子链间倾向于edge-on堆积方式。相比纯PffBT4T-2DT薄膜,共混薄膜具有优异的可拉伸性能,使其在100%的高拉伸应变下仍保持较高的载流子迁移率。这源于弹性的PDMS基体有效地耗散拉伸产生的薄膜内部能量。基于柔性薄膜结构表征,分析了薄膜微结构与其力学性质和电荷传输性能间的内在联系。

The blend films are prepared by spin-coating the solution of a benzothiadiazole-based semiconducting polymer PffBT4T-2DT mixed with the elastomer polydimethylsiloxane(PDMS),and organic field effect transistors(OFETs)have then been constructed via a contact lamination transfer process to evaluate electrical performance of these blend films under strain.It reveals a vertically phase-separated structure in the PffBT4T-2DT/PDMS blend films,in which PffBT4T-2DT is enriched mainly in the lower layer of the film and the PDMS at the upper part.The introduction of PDMS in the blend also promotes the formation of edge-on stacking motif of the PffBT4T-2DT backbones.Notably,compared to pristine PffBT4T-2DT,the blend films exhibit significantly improved strain tolerance(stretchability),which ensures a relatively high hole mobility in OFETs even under 100%strain.The enhancement of elasticity and carrier mobility should be attributed to the PDMS matrix which effectively dissipate the energy inside the mechanically stretched film.Furthermore,the correlation between the film structure,mechanical properties and carrier transport of the blend film is clarified,based on the structural characterizations.