Filters

2020 - 20223

More filters

2021 - 20233
Reset filters

Settings

Author: Heine, Thomas × WGL Institute: IPF ×

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    A Two-Dimensional Polyimide-Graphene Heterostructure with Ultra-fast Interlayer Charge Transfer
    (Weinheim : Wiley-VCH, 2021) Liu, Kejun; Li, Jiang; Qi, Haoyuan; Hambsch, Mike; Rawle, Jonathan; Vázquez, Adrián Romaní; Nia, Ali Shaygan; Pashkin, Alexej; Schneider, Harald; Polozij, Mirosllav; Heine, Thomas; Helm, Manfred; Mannsfeld, Stefan C.B.; Kaiser, Ute; Dong, Renhao; Feng, Xinliang
    Two-dimensional polymers (2DPs) are a class of atomically/molecularly thin crystalline organic 2D materials. They are intriguing candidates for the development of unprecedented organic–inorganic 2D van der Waals heterostructures (vdWHs) with exotic physicochemical properties. In this work, we demonstrate the on-water surface synthesis of large-area (cm2), monolayer 2D polyimide (2DPI) with 3.1-nm lattice. Such 2DPI comprises metal-free porphyrin and perylene units linked by imide bonds. We further achieve a scalable synthesis of 2DPI-graphene (2DPI-G) vdWHs via a face-to-face co-assembly of graphene and 2DPI on the water surface. Remarkably, femtosecond transient absorption spectroscopy reveals an ultra-fast interlayer charge transfer (ca. 60 fs) in the resultant 2DPI-G vdWH upon protonation by acid, which is equivalent to that of the fastest reports among inorganic 2D vdWHs. Such large interlayer electronic coupling is ascribed to the interlayer cation–π interaction between 2DP and graphene. © 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH
  • Thumbnail Image
    Item
    STM-induced ring closure of vinylheptafulvene molecular dipole switches on Au(111)
    (Cambridge : Royal Society of Chemistry, 2022) Au-Yeung, Kwan Ho; Kühne, Tim; Aiboudi, Oumaima; Sarkar, Suchetana; Guskova, Olga; Ryndyk, Dmitry A.; Heine, Thomas; Lissel, Franziska; Moresco, Francesca
    Dihydroazulene/vinylheptafulvene pairs are known as molecular dipole switches that undergo a ring-opening/-closure reaction by UV irradiation or thermal excitation. Herein, we show that the ring-closure reaction of a single vinylheptafulvene adsorbed on the Au(111) surface can be induced by voltage pulses from the tip of a scanning tunneling microscope. This cyclization is accompanied by the elimination of HCN, as confirmed by simulations. When inducing lateral movements by applying voltage pulses with the STM tip, we observe that the response of the single molecules changes with the ring closing reaction. This behaviour is discussed by comparing the dipole moment and the charge distribution of the open and closed forms on the surface.
  • Thumbnail Image
    Item
    Two-Dimensional Boronate Ester Covalent Organic Framework Thin Films with Large Single Crystalline Domains for a Neuromorphic Memory Device
    (Weinheim : Wiley-VCH, 2020) Park, SangWook; Liao, Zhongquan; Ibarlucea, Bergoi; Qi, Haoyuan; Lin, Hung-Hsuan; Becker, Daniel; Melidonie, Jason; Zhang, Tao; Sahabudeen, Hafeesudeen; Baraban, Larysa; Baek, Chang-Ki; Zheng, Zhikun; Zschech, Ehrenfried; Fery, Andreas; Heine, Thomas; Kaiser, Ute; Cuniberti, Gianaurelio; Dong, Renhao; Feng, Xinliang
    Despite the recent progress in the synthesis of crystalline boronate ester covalent organic frameworks (BECOFs) in powder and thin-film through solvothermal method and on-solid-surface synthesis, respectively, their applications in electronics, remain less explored due to the challenges in thin-film processability and device integration associated with the control of film thickness, layer orientation, stability and crystallinity. Moreover, although the crystalline domain sizes of the powder samples can reach micrometer scale (up to ≈1.5 μm), the reported thin-film samples have so far rather small crystalline domains up to 100 nm. Here we demonstrate a general and efficient synthesis of crystalline two-dimensional (2D) BECOF films composed of porphyrin macrocycles and phenyl or naphthyl linkers (named as 2D BECOF-PP or 2D BECOF-PN) by employing a surfactant-monolayer-assisted interfacial synthesis (SMAIS) on the water surface. The achieved 2D BECOF-PP is featured as free-standing thin film with large single-crystalline domains up to ≈60 μm2 and tunable thickness from 6 to 16 nm. A hybrid memory device composed of 2D BECOF-PP film on silicon nanowire-based field-effect transistor is demonstrated as a bio-inspired system to mimic neuronal synapses, displaying a learning–erasing–forgetting memory process. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.