半导体聚合物/石墨烯共混薄膜的强磁诱导生长及其电荷传输研究

Magnetic field guided film growth for improved carrier transport properties of the semiconducting polymer/graphene nanocomposites

我们将P(NDI2OD-T2)等半导体聚合物与石墨烯纳米片通过溶液相共混,制备了薄膜场效应晶体管(OFET)。发现无论是P型还是N型器件,掺混石墨烯都显著地提高其载流子迁移率。并且采用强磁场下的溶液滴涂方法来生长P(NDI2OD-T2)/石墨烯共混薄膜,获得了高取向薄膜。发现相比于"纯"半导体聚合物,加入少量的石墨烯纳米片可显著提高共混薄膜中聚合物主干链取向程度、增强OFET器件的电子迁移率各向异性。此外还利用旋转磁场来调控薄膜中主干链共轭平面的面外方向取向,进一步了提高薄膜的电荷传输性能。我们认为,P(NDI2OD-T2)链聚集体与石墨烯π平面构成的组合体可增强主干链取向并在聚合物畴界处形成快速的电荷传输通路,从而提高薄膜的电荷传输。

In this work,graphene nano-sheets were incorporated into the matrix of semiconducting polymers P(NDI2 OD-T2)and DPP-2 T via solution mixing for the film preparation.The process results in a remarkable enhancement of carrier mobility on both N-type and P-type polymeric field-effect transistors(FETs).Furthermore,the aligned films of the P(NDI2 OD-T2)/graphene composites have been achieved by solution drop-cast under high magnetic field.It reveals that the incorporation of small amount of graphene sheets improved the degree of chain alignment,and consequently enhanced the anisotropy of electron mobility of the OFETs compared to pristine P(NDI2 OD-T2).The charge transport properties of the composite films were also improved via the film growth under a rotating magnetic field,which should originate from the enhanced face-on packing of P(NDI2 OD-T2)by magnetically controlling the orientation of conjugated planes of the backbones.It suggests that the ensembles of polymer aggregated on the graphene planes facilitated magnetic alignment as well as the formation of fast conduction pathways at the polymer domain boundaries.