Strengthening of Molecule-Electrodes Contacts by the Use of Modified Curcuminoids in Hybrid Graphene Transistors
Enrique Burzurí,1 Joshua O. Island,1 Raúl Díaz-Torres,2,3 Alexandra Fursina,1 Arántzazu González-Campo,3 Olivier Roubeau,4 Simon J. Teat,5 Núria Aliaga-Alcalde,3,6, Eliseo Ruiz,2 and Herre S. J. van der Zant1
Sequential Electron Transport and Vibrational Excitations in an Organic Molecule Coupled to Few-Layer Graphene Electrodes ACS Nano, 10 (2), 2521-2527, 2016
Idealized roadmap for the achievement of single-molecule three-terminal nanodevices based on graphene and Curcuminoid molecules.
The use of molecules, in electronic devices, will allow the creation at the nanoscale of reliable wires, diodes and switches, having a large impact in a number of nanotechnological areas and therefore, in advanced applications (chips, communications, computers affecting therefore drug discovery, bioinformatics, medical imaging and diagnostics, among others). However, the implementation of functional molecular-based nanodevices in present technologies is mainly hampered by crucial unresolved issues like the reliability of room temperature experiments on molecular transistors, the absence of controlled methodologies to deposit single molecules at specific sites, low conductance values and the difficulties in achieving effective three-terminal devices (transistors). Such hindrances involve the nature of the molecules, the absence of controlled deposition methodologies at the nanoscale and the poor stability/contacts between molecules and electrodes.
In the last years, the group of Núria Aliaga has synthesized a selected family of Curcuminoid molecules (CCMoids) toward their use as molecular components in gateable molecular junctions based on graphene. By joining common interests, our physicist collaborators and we presented reasonable conductance values at room temperature by the use of an original CCMoid that cleavage to graphene electrodes through π- π stacking.
Here, by the creation of a new CCMoid (molecule highlighted in the Figure) we have found the co-existence of excitations of vibrational nature with single electron transport physics at low temperatures. Such vibrational assisted excitations are rarely observed in molecules attached to graphene. Now, our findings at low temperatures are improved results with respect to the case former CCMoid systems (under the same conditions), because demonstrate an enhancement of the coupling between the graphene electrodes and the anthracene groups of the new molecule. Our working hypothesis was that enlarging the conjugated skeleton of the molecule would assist the coupling being further from the edges of the graphene electrodes. We have also proved that enlarging the CCMoid, but improving the contact with electrodes, does not damage the final conductance values.
1 Kavli Institute of Nanoscience, Delft University of Technology, The Netherlands 2 Departament de Química Inorgànica and Institut de Recerca de Química Teòrica i Computacional, Universitat de Barcelona, Spain 3 Institut de Ciència dels Materials de Barcelona (ICMAB-CSIC), Spain 4 Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC, and Universidad de Zaragoza, Spain 5 Advanced Light Source, Lawrence Berkeley National Laboratory, USA 6 ICREA (Institució Catalana de Recerca i Estudis Avançats), Spain
Institut de Ciència de Materials de Barcelona Campus de la UAB 08193 Bellaterra, SPAIN