van Geest Erik P, Shakouri Khosrow, Fu Wangyang, Robert Vincent, Tudor Viorica, Bonnet Sylvestre, Schneider Grégory F
Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands.
Laboratoire de Chimie Quantique, Université de Strasbourg, CNRS, UMR 7177, 67081, Strasbourg, France.
Adv Mater. 2020 Mar;32(10):e1903575. doi: 10.1002/adma.201903575. Epub 2020 Feb 3.
Direct electrical probing of molecular materials is often impaired by their insulating nature. Here, graphene is interfaced with single crystals of a molecular spin crossover complex, [Fe(bapbpy)(NCS) ], to electrically detect phase transitions in the molecular crystal through the variation of graphene resistance. Contactless sensing is achieved by separating the crystal from graphene with an insulating polymer spacer. Next to mechanical effects, which influence the conductivity of the graphene sheet but can be minimized by using a thicker spacer, a Dirac point shift in graphene is observed experimentally upon spin crossover. As confirmed by computational modeling, this Dirac point shift is due to the phase-dependent electrostatic potential generated by the crystal inside the graphene sheet. This effect, named as chemo-electric gating, suggests that molecular materials may serve as substrates for designing graphene-based electronic devices. Chemo-electric gating, thus, opens up new possibilities to electrically probe chemical and physical processes in molecular materials in a contactless fashion, from a large distance, which can enhance their use in technological applications, for example, as sensors.
分子材料的绝缘性质常常阻碍对其进行直接的电探测。在此，石墨烯与分子自旋交叉配合物[Fe(bapbpy)(NCS)]的单晶相结合，通过石墨烯电阻的变化来电检测分子晶体中的相变。通过用绝缘聚合物间隔层将晶体与石墨烯分离来实现非接触式传感。除了会影响石墨烯片层电导率但可通过使用更厚的间隔层使其最小化的机械效应外，实验观察到在自旋交叉时石墨烯中的狄拉克点发生了移动。经计算建模证实，这种狄拉克点移动是由石墨烯片层内晶体产生的与相相关的静电势所致。这种效应被称为化学电门控，表明分子材料可用作设计基于石墨烯的电子器件的衬底。因此，化学电门控开启了以非接触方式从远距离对分子材料中的化学和物理过程进行电探测的新可能性，这可增强其在技术应用（例如作为传感器）中的用途。
