Laser printing of 2D materials
LIFT of 2D Layered Materials
2D Layered Materials hold enormous promise for enabling new device concepts and novel applications, owing to their planar nature and their exquisite, tunable properties. In this study, which is part of the project LEAF-2D (https://www.leaf2d.eu) that has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 801389, we aim to transfer single layer, defect-free graphene pixels on flexible substrates for highly sensitive ultra-thin sensors using laser printing.
LIFT of graphene oxide for chemical sensors.
Graphene-related materials (graphene oxide-GO, reduced graphene oxide-rGO) present unique properties that can be exploited for the fabrication of devices including chemical sensors, biosensors, etc. In our lab, we employ LIFT, to selectively print GO, both at liquid phase (GO dispersions) and solid phase (thin films of GO) on the substrates of interest, aiming to incorporate the printed structures into chemical sensors. Since GO is an insulating material, to render it conductive we employ thermal and laser-assisted reduction approaches as shown in the following paragraphs.
LIFT and thermal reduction of graphene oxide
Thermal reduction introduces a significant number of vacancies and/or defects on the GO surface, which is mainly covered by hydroxyl and epoxy groups on its basal plane as well as carbonyl and carboxyl groups at the edges of the flakes. We exploit these vacancies that act as binding sites for the gaseous molecules to use rGO in chemical sensors.
Sequential laser printing and laser reduction of graphene oxide
This sequential laser transfer and laser reduction process, occurs rapidly (under 1 sec) employing two consecutive picosecond (ps) pulses per transferred and reduced GO spot and can be easily scaled up, allowing for the rapid fabrication of conductive micro-structures. Our method exhibits a lateral resolution of 20 μm.
LIFT of liquid-phase exfoliated graphene
We employ LIFT for the printing of liquid-phase exfoliated graphene on rigid and flexible substrates to create arbitrary conductive patterns.