Graphene field-effect transistor structures were used to investigate the role of molecular alignment on charge transport properties of heterostructures comprising a single-layer graphene and variable thickness of N,N′-bis(n-octyl)-(1,7&1,6)-dicyanoperylene-3,4:9,10-bisdicarboximide (PDI8-CN2) - an n-type organic semiconductor. Our atomic force microscopy data show that under selected growth conditions PDI8-CN2 grows in a layer-by-layer fashion up to a second monolayer. The first layer comprises flat-lying molecules, whereas the molecules in the second layer orient themselves in an upright orientation. Transconductance measurements show that the flat-lying molecules have little effect on the position of the Fermi level in graphene. Upright oriented molecules in the second layer instead, have a strong effect as to neutralize native p-type doping of graphene and cause a shift of charge-neutrality level towards the Dirac point. We interpret such behavior in terms of different orientation of the surface dipole on layers with different molecular orientations. At the same time the overall mobility of the charge carriers reaches values exceeding 3000 cm²/Vs.

使用石墨烯场效应晶体管结构研究分子排列对包含单层石墨烯和可变厚度的N，N'-双（n-辛基）-（1,7＆1,6）的异质结构的电荷传输性质的作用-二氰基亚戊基-3,4：9,10-双二芳基酰亚胺（PDI8-CN2）-一种n型有机半导体。我们的原子力显微镜数据显示，在选定的生长条件下，PDI8-CN2逐层生长直至第二个单层。第一层包含平坦的分子，而第二层中的分子将自身定向为直立方向。跨导测量表明，平坦分子对石墨烯中费米能级的位置影响很小。相反，第二层中的垂直取向分子对中和天然分子具有强大的作用石墨烯的p型掺杂会导致电荷中性能级移向Dirac点。我们用不同分子取向的层上表面偶极子的不同取向来解释这种行为。同时，电荷载流子的总迁移率达到超过3000cm ² / Vs的值。