Layer-By-Layer assembly of two-dimensional polymer/ graphene heterostructures as wafer-scale flexible opto-electronics
Van der Waals heterostructures (vdWHs) of atomically thin, two-dimensional (2D) materials have been attracting a wide range of research interests since their unique structures enable tunable and customized optical, electronic and magnetic properties. The vertical layer-by-layer assembly strategies make it feasible to mix and match different 2D materials into various vdWHs without the restraint of lattice matching and processing compatibility. Currently, however, most of 2D vdWHs (termed ‘2DvdWHs’) are predominantly based on inorganic sandwich complexes, especially on graphene, transition metal dichalcogenides (TMDCs) and hexagonal boron-nitride (hBN). What’s more, the vertical assembly method for 2DvdWHs mainly limits to small-scale proof-of-concept demonstrations. Consequently, I will develop a new generation of vdWHs through layer-by-layer assembling monolayer 2D polymers (2DPs) with monolayer graphene (Gr) for wafer-scale, flexible opto-electronics. The 2D organic-inorganic interface can engineer the field-induced charge-carrier transport within the 2DP-Gr heterostructures, and thus tailor their opto-electronic properties. The core technology is the advanced monolayer 2DPs synthesized at the air/water interface via Langmuir–Blodgett (LB) techniques based on photo-active conjugated monomers, such as porphyrin and pyrene derivatives. The resulting 2DPs are designed to be freestanding, monolayer semi-conductors with tuned band gaps and photo responses. Importantly, this technology can be extended to other 2D materials (e.g. TMDCs and hBN) and monomers, which structures can be further optimized for the better flexibility of the band gaps, higher enhancement of the charge transfer, and the new introduction of the photoactivity. A critical aspect of the work will be the use of customized 2DPs to integrate with Gr as wafer-scale, tunable 2DvdWHs and to study the unique quantum phenomena that arise from the organic-inorganic interlayer coupling.