Evidence for Band‐Like Transport in Graphene‐Based Organic Monolayers

Abstract

Evidence for a band‐like, lateral transport of electrons through the cores of HBC‐thiolates, forming a highly ordered self‐assembled monolayer (SAM) containing a very regular array of HBC‐cores, is provided based on a detailed analysis of temperature‐dependent scanning tunneling microscopy (STM) data recorded for islands of aromatic SAMs immersed in an insulating matrix.

Charge carrier mobilities in organic semiconductors: crystal engineering and the importance of molecular contacts

“…Similar to the previous system, 45 the STM data in Fig. 3 show extraordinary long range ordered domains of parallel lamella rows of HBC_C2 SAMs.…”

“…Obviously, the fact that the Au(111) reconstruction survives the HBC_C1 SAM-formation (HBC with mono thiolate-anchors) is a result of the fairly low density of the thiolate groups (149 Å 2 (ref. 45) vs. 21.65 Å 2 (ref. 47) for a normal, thiolate-based SAM).…”

“…44 In earlier experiments it was demonstrated, however, that molecular arrangements containing 1-d rows of HBC-cores could be realized in the form of self-assembled monolayers (SAMs) by employing HBC_C1, a HBC derivative to which one thiolate anchor and five solubilizing alkyl chains were attached. 45 These HBC SAMs formed by spontaneous surface grafting were characterized by high-resolution microscopy (scanning tunneling microscopy, STM) and near edge X-ray absorption-spectroscopy (NEXAFS) 45 and found to correspond to quasi-1D packing with twisting angles of 01 between adjacent cores. Here, the unfavorable intermolecular interaction is compensated through the boundary condition imposed by anchoring HBC-cores via the thiolate-groups to the Au-substrate, yielding stacks of tilted but eclipsed HBC cores.…”

Structure–charge transfer property relationship in self-assembled discotic liquid-crystalline donor–acceptor dyad and triad thin films

“…[19][20][21][22][23][24] Possible control of the energy and the charge transfer processes together with the existence of percolation pathways for both holes and electrons via the formation of well-dened, nanosegregated donoracceptor domains are indeed of critical importance for enhancing photovoltaic performances. Among the variety of LC donor-acceptor (D-A) materials developed so far, [25][26][27][28] covalently linked electron D-A dyad and triad molecules are of interest as their self-assembly can produce highly ordered wellseparated structures of well-stacked D and A p-molecules. [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46] In such supramolecular systems, excitons are photogenerated close to the D-A interface and pathways for hole and electron transport are well dened, providing a suitable conguration for efficient formation of excited charge transfer (CT) states and ambipolar charge transport.…”

Interfacial Systems Chemistry: Out of the Vacuum—Through the Liquid—Into the Cell

“…[22,23] Ulman and his colleagues investigated the structure of functionalized biphenyl-SAMs by infrared spectroscopy and X-ray diffraction and proposed models for complete (high-density phase) and partial (low-density phase) coverage. [24,25] Recently, interest in aromatic SAMs increased strongly due to their use in molecular electronics, [26] organic electronics, [27] and nanolithography. [28] The orientation and order in biphenyl-based SAMs depends in a rather complicated way on the fixation-induced packing and the resulting intermolecular interactions within the organic ultrathin layer.…”