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Xin Xu1 Beilei Sun1 Zefeng Chen1 Jianbin Xu1

1, The Chinese University of Hong Kong, Shatin, , Hong Kong

Charge transport properties near the interface of organic materials which constitute the intrinsic characteristics of carriers is one of the most fundamental research fronts of organic transistors, particularly organic field-effect transistors (OFETs). Despite of the successful fabrication of bulk organic crystals, it is very challenging to interrogate the interface properties with three-dimensional (3D) organic materials. Therefore high-quality 2D electroactive organic layered materials with highly ordered molecular packing is an ideal platform to conduct this kind of research and development. Here, by utilizing physical vapor transport method (PVT), we produce highly-ordered, large-area and controllably-thick layers of 2D N,N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13) with 10 nm in the maximum thickness. We find that the transport behavior of the single layer (1L) and the bilayer (2L) of PTCDI-C13 is of significant difference. In the 1L device, the transport behavior is predominately attributed to the hopping mechanism, while in the 2L device, the transport characteristics are dominated first by the band-like mechanism, and then by the hopping mechanism as the device temperature is reduced lower than 240 K. Meanwhile, when the layer thickness is increased from 1L to 2L, the carrier mobility anisotropy decreases significantly from 5.0 to 1.5. This marked difference is ascribed to the different steric arrangement of molecules. Our results unambiguously corroborate the intrinsic charge transport properties of electroactive organic layered materials at the interfaces.

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