Supramolecular self-assembly offers a feasible route for nanopatterning and functionality. The construction and precise control of selective adsorption at the molecular scale play essential roles in fundamental sciences and practical applications. Molecular tiling such as trihexagonal tiling Kagome networks has potential promising chemical and physical properties. Distorted Kagome-like networks controllable fabrication is possible by coupling molecular functional groups and substrate atoms. A chiral Kagome-like network was constructed using IFDO ([1,2-b]fluorene-6,12-dione) as precursor molecules complemented with molecular beam epitaxy and annealing strategies. Revealing arrangements of the assembled network of O-Cu metal coordination linked Kagome-like networks on the Cu(1 1 1) surface and their assembly mechanisms and cavity characteristics were explored in detail through scanning tunneling microscopy combined with density functional theory. Based on the electronic state difference between the hole center of the network and the molecular backbone, the host–guest network was successfully prepared by co-depositing C 60 molecules. Kagome-like networks could as an efficient template for regulating the adsorption configuration of C 60 . Our results demonstrate a controllable and efficient method to design atomically precise ordered host–guest assemblies on solid surfaces, advancing the approach is yet another step toward the fabrication of molecular devices.
Qing Bao,Hua Li,Yang Li,Jinghui He,Qingfeng Xu,Najun Li,Dongyun Chen,Lihua Wang,Jianmei Lu
In this paper, two acceptor-donor-acceptor (A-D-A) type organic small molecules, 4,4'-(5,5'-(benzo[c] [1,2,5]thiadiazole-4,7-diyl)bis(3-hexylthiophene-5,2-diyl))bis(N-(4-nitrophenyl)-N-phenylaniline) (NTPA 2 TBT) and 4,4'-(5,6-difluorobenzo[c] [1,2,5]thiadiazole-4,7-diyl)bis(N-(4-nitrophenyl)-N-phenylaniline) (NTPA 2 BTF 2 ), were synthesized and fabricated into resistive random access memory devices. Compared with our previously reported molecule NTPA 2 BT, NTPA 2 TBT has 3-hexylthiophene linkages bridging its donor and acceptor, while there are two additional fluorine atoms in the benzothiadiazole moiety for NTPA 2 BTF 2. Both the fabricated memory devices based on these two new molecules perform nonvolatile ternary memory characteristics with lower threshold voltages , higher reproducibility and better stability. The addition of 3-hexylthiophene bridges significantly promotes the planarity of the conjugation backbone and facilitates the molecular stacking, while the substitution hydrogen by fluorine improves the intermolecular interaction , and thus also induces an ordered molecular stacking. The insertion of 3-hexylthiophene bridges or fluorine atoms could be an effective strategy of tailoring organic molecules to improve data storage performance with lower power consumption.
Yang Feng,Xu Gao,Ya-Nan Zhong,Jia-Ling Wu,Jian-Long Xu,Sui-Dong Wang
Emerging organic synaptic devices are promising in exploring soft and biocompatible neuromorphic computing systems. By means of a simple and low-cost solution process, the polymer thin-film memristors are designed and characterized. The polymer memristors have a bilayer structure composed of an ion-rich semiconducting layer and an ion-collecting conducting layer, where the ion redistribution depending on device operation history has an impact on carrier concentration and results in the memristive characteristics. A visible electrochromic feature is observed during the electrical measurements, supporting the proposed Li + ion drift/diffusion mechanism. The polymer memristors show the continuous and reversible conductivity tuning with a temporary memory effect, which enables the successful emulation of the frequency-dependent synaptic plasticity. The polymer thin-film memristors may offer a strategy for developing building blocks of organic neuromorphic circuits.
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