The deposition and organization of monolayers, multilayers and heterostructures of organic molecules on the insulating hexagonal boron nitride (hBN) is studied using ambient atomic force microscopy. It is possible to form extended supramolecular arrays of molecules stabilized by hydrogen bonding between carboxylic groups using molecules such as tetrakis (4-carboxyphenyl) porphyrin (TCPP), terphthalic acid (TPA) and trimesic acid (TMA) which form respectively square, row and honeycomb arrays when deposited from ethanolic solutions. We have also studied bi-component systems such as melamine cyanurate and the combination of perylene tetracarboxylic di-imide (PTCDI) and melamine which form extended highly ordered arrays on hBN. We have also found that sequential deposition of layers is possible and find orientationally controlled epitaxial growth of TPA, TMA, TCPP and PTCDI on melamine cyanurate. This is possible for both monolayers, multilayers and nanocrystals of melamine cyanurate. The energetics controlling the growth of heterostructures has been investigated using molecular dynamics calculations and we find excellent agreement between theory and experiment. The use of the hBN substrate also facilitates the measurement of the fluorescence of adsorbed organic layers and we find shifts in the emission peak position when TCPP is adsorbed on melamine cyanurate which are explained using time-dependent density functional theory. We also discuss interference effects arising from the highly parallel interfaces of the hBN flakes and discuss how these effects can the optical properties of fluorophores which can be integrated into supramolecular heterostructures.

Supramolecular arrays and heterostructures on hexagonal boron nitride

253rd National Meeting (2017)

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