Interdisciplinary School of Green Energy, Low Dimensional Carbon Materials Center, KIER-UNIST Advanced Center for Energy, Ulsan National Institute of Science & Technology (UNIST), UNIST-gil 50, Ulsan 689-805, Korea.
ACS Nano. 2012 Oct 23;6(10):9207-13. doi: 10.1021/nn303539y. Epub 2012 Sep 20.
Graphene has been functionalized with spiropyran (SP), a well-known photochromic molecule. It has been realized with pyrene-modified SP, which has been adsorbed on graphene by π-π interaction between pyrene and graphene. The field-effect transistor (FET) with SP-functionalized graphene exhibited n-doping effect and interesting optoelectronic behaviors. The Dirac point of graphene in the FET could be controlled by light modulation because spiropyran can be reversibly switched between two different conformations, a neutral form (colorless SP) and a charge-separated form (purple colored merocyanine, MC), on UV and visible light irradiation. The MC form is produced during UV light irradiation, inducing the shift of the Dirac point of graphene toward negative gate voltage. The reverse process back to the neutral SP form occurred under visible light irradiation or in darkness, inducing a shift of the Dirac point toward positive gate voltage. The change of the Dirac point by UV and visible light was reproducibly repeated. SP molecules also improved the conductance change in the FET device. Furthermore, dynamics on conversion from MC to SP on graphene was different from that in solution and solid samples with SP-grafted polymer or that on gold nanoparticles.
石墨烯已用螺吡喃（SP）进行功能化，螺吡喃是一种众所周知的光致变色分子。已通过吸附在石墨烯上的芘改性 SP 来实现，芘与石墨烯之间的π-π相互作用将 SP 吸附在石墨烯上。具有 SP 功能化石墨烯的场效应晶体管（FET）表现出 n 型掺杂效应和有趣的光电行为。由于螺吡喃可以在紫外线和可见光照射下可逆地在两种不同构象之间切换，即中性形式（无色 SP）和电荷分离形式（紫色的变色体 MC），因此 FET 中石墨烯的狄拉克点可以通过光调制来控制。MC 形式在紫外线照射下产生，导致石墨烯的狄拉克点向负栅极电压移动。在可见光照射或黑暗中，逆过程回到中性 SP 形式，导致狄拉克点向正栅极电压移动。狄拉克点的这种由紫外线和可见光引起的变化可以重复再现。SP 分子还改善了 FET 器件中的电导变化。此外，在石墨烯上从 MC 到 SP 的转换动力学与在含有 SP 接枝聚合物的溶液和固体样品中或在金纳米粒子上的动力学不同。
