Lifeng Chi

Publications of Lifeng Chi

• The Electrode's Effect on the Stability of Organic Transistors and Circuits.

  Authors: Liqiang Li, Karin Meise-Gresch, Lin Jiang, Chuan Du, Wenchong Wang, Harald Fuchs, Lifeng Chi

  Advanced materials (Deerfield Beach, Fla.). 05/2012;

  A new understanding and a promising solution for the stability of organic transistors and circuits are presented. The electrodes are demonstrated to play an unexpectedly important role on the deviceA new understanding and a promising solution for the stability of organic transistors and circuits are presented. The electrodes are demonstrated to play an unexpectedly important role on the device stability. Au electrodes exert a detrimental effect on the device stability, while the overall device stability of p-/n-type transistors and complementary inverter circuits is improved significantly by using conducting polypyrrole (PPY) electrodes.

• High-Performance and Stable Organic Transistors and Circuits with Patterned Polypyrrole Electrodes.

  Authors: Liqiang Li, Lin Jiang, Wenchong Wang, Chuan Du, Harald Fuchs, Wenping Hu, Lifeng Chi

  Advanced materials (Deerfield Beach, Fla.). 03/2012;

  High performance p-/n-type transistors and complementary inverter circuits are demonstrated using patterned polypyrrole (PPY) as pure electrodes. Strikingly, these devices show good stability underHigh performance p-/n-type transistors and complementary inverter circuits are demonstrated using patterned polypyrrole (PPY) as pure electrodes. Strikingly, these devices show good stability under continuous operation and long-term storage conditions. Furthermore, PPY electrodes also exhibit good applicability in solution-processed and flexible devices. All these results indicate the great potential of PPY electrodes in solution-processed, all-organic, flexible, transparent, and low-power electronics.

• TRR 61, the "interplay" between Münster and Beijing for promoting research on multilevel molecular assemblies: structure, dynamics, and functions.

  Authors: Harald Fuchs, Xi Zhang, Lifeng Chi, Deqing Zhang

  Small (Weinheim an der Bergstrasse, Germany). 02/2012; 8(4):479-80, 477.

• Molecular cloisonné: multicomponent organic alternating nanostructures at vicinal surfaces with tunable length scales.

  Authors: Dingyong Zhong, Lifeng Chi, Haiming Guo, Dongxia Shi, Harald Fuchs

  Small (Weinheim an der Bergstrasse, Germany). 02/2012; 8(4):535-40.

  By careful management of the adsorption preference of organic molecules at faceted vicinal surfaces, organic alternating structures can be extended to multilayers and multicomponent with tunable sizeBy careful management of the adsorption preference of organic molecules at faceted vicinal surfaces, organic alternating structures can be extended to multilayers and multicomponent with tunable size scales ranging from several to a few tens nanometers.

• Different growth regimes on prepatterned surfaces: consistent evidence from simulations and experiments.

  Authors: Fabian Lied, Tanja Mues, Wenchong Wang, Lifeng Chi, Andreas Heuer

  The Journal of chemical physics. 01/2012; 136(2):024704.

  Molecule deposition on a prepatterned substrate is a recently developed technique to generate desired structures of organic molecules on surfaces via self-organization. For the case of prepatternedMolecule deposition on a prepatterned substrate is a recently developed technique to generate desired structures of organic molecules on surfaces via self-organization. For the case of prepatterned stripes, the time-resolved process of structure formation is studied via lattice Monte Carlo simulations. By systematic variation of the interaction strength, three distinct growth regimes can be identified: localized growth, bulge formation, and cluster formation. All three growth regimes can be recovered in the experiment when choosing appropriate organic molecules. Some key microscopic observables, reflecting the properties of the structure formation, display a non-monotonous dependence on the interaction strength.

• Fabrication of hierarchical structures by unconventional two-step imprinting.

  Authors: Gang Shi, Nan Lu, Hongbo Xu, Yandong Wang, Shoulei Shi, Hui Li, Ying Li, Lifeng Chi

  Journal of colloid and interface science. 12/2011; 368(1):655-9.

  We present a simple sequential imprinting lithography method to fabricate micro/nanoscale hierarchical structures. This method involves hot embossing and capillary force lithography with two stampsWe present a simple sequential imprinting lithography method to fabricate micro/nanoscale hierarchical structures. This method involves hot embossing and capillary force lithography with two stamps of different microscales, which avoids using nanoscale stamps. By varying the experimental conditions in the capillary force lithography process, the morphology of the resulting structures can be controlled. This method may provide a facile and low-cost route for fabricating large area patterns of hierarchical structures.

• Fabrication of periodic metal nanowires with microscale mold by nanoimprint lithography.

  Authors: Shoulei Shi, Nan Lu, Yongchun Lu, Yandong Wang, Dianpeng Qi, Hongbo Xu, Lifeng Chi

  ACS applied materials & interfaces. 11/2011; 3(11):4174-9.

  In this paper, a simple method is demonstrated for fabricating periodic metal nanowires based on the unconventional nanoimprint lithography (NIL) technique. Using this method, sub-100 nm metalIn this paper, a simple method is demonstrated for fabricating periodic metal nanowires based on the unconventional nanoimprint lithography (NIL) technique. Using this method, sub-100 nm metal nanowires with the rectangular cross-section are fabricated with microscale stamp. Furthermore, the metal nanowires with different widths and heights can be generated by adjusting the imprinting parameters with the same stamp. The metal nanowires prepared with this method can be used for chemical sensing, such as ammonia sensing, and it may have applications in optical signal processing.

• Linear alkane polymerization on a gold surface.

  Authors: Dingyong Zhong, Jörn-Holger Franke, Santhosh Kumar Podiyanachari, Tobias Blömker, Haiming Zhang, Gerald Kehr, Gerhard Erker, Harald Fuchs, Lifeng Chi

  Science (New York, N.Y.). 10/2011; 334(6053):213-6.

  In contrast to the many methods of selectively coupling olefins, few protocols catenate saturated hydrocarbons in a predictable manner. We report here the highly selective carbon-hydrogen (C-H)In contrast to the many methods of selectively coupling olefins, few protocols catenate saturated hydrocarbons in a predictable manner. We report here the highly selective carbon-hydrogen (C-H) activation and subsequent dehydrogenative C-C coupling reaction of long-chain (>C(20)) linear alkanes on an anisotropic gold(110) surface, which undergoes an appropriate reconstruction by adsorption of the molecules and subsequent mild annealing, resulting in nanometer-sized channels (1.22 nanometers in width). Owing to the orientational constraint of the reactant molecules in these one-dimensional channels, the reaction takes place exclusively at specific sites (terminal CH(3) or penultimate CH(2) groups) in the chains at intermediate temperatures (420 to 470 kelvin) and selects for aliphatic over aromatic C-H activation.

• Patterning of plasmonic nanoparticles into multiplexed one-dimensional arrays based on spatially modulated electrostatic potential.

  Authors: Lin Jiang, Yinghui Sun, Christoph Nowak, Asmorom Kibrom, Changji Zou, Jan Ma, Harald Fuchs, Shuzhou Li, Lifeng Chi, Xiaodong Chen

  ACS nano. 09/2011; 5(10):8288-94.

  We report a new strategy to pattern plasmonic nanoparticles into multiplexed one-dimensional arrays based on the spatially modulated electrostatic potential. The 32 nm Au nanoparticles can beWe report a new strategy to pattern plasmonic nanoparticles into multiplexed one-dimensional arrays based on the spatially modulated electrostatic potential. The 32 nm Au nanoparticles can be simultaneously deposited on one chip with tunable interparticle distance by solely adjusting the width of the grooves. Furthermore, 32 and 13 nm Au nanoparticles can be selectively deposited in grooves of different widths on one chip. As a result, the surface plasmon absorption bands on the chip can be tuned depending on the interparticle distance or the particle size of multiplex 1D arrays, which could enhance the Raman scattering cross section of the adsorbed molecules and result in multiplex surface-enhanced Raman scattering (SERS) response on the chip. This strategy provides a general method to fabricate 1D multiplex arrays with different particle sizes and interparticle distances on one chip.

• Chemical surface modification of self-assembled monolayers by radical nitroxide exchange reactions.

  Authors: Hendrik Wagner, Marion K Brinks, Michael Hirtz, Andreas Schäfer, Lifeng Chi, Armido Studer

  Chemistry (Weinheim an der Bergstrasse, Germany). 08/2011; 17(33):9107-12.

  This article describes the application of nitroxide exchange reactions of surface-bound alkoxyamines as a tool for reversible chemical modification of self-assembled monolayers (SAMs). This approachThis article describes the application of nitroxide exchange reactions of surface-bound alkoxyamines as a tool for reversible chemical modification of self-assembled monolayers (SAMs). This approach is based on radical chemistry, which allows for introduction of various functional groups and can be used to reversibly introduce functionalities at surfaces. To investigate the scope of this surface chemistry, alkoxyamines with different functionalities were synthesized and were then applied to the immobilization of, for example, dyes, sugars, or biotin. Surface analysis was carried out by contact angle, X-ray photoelectron spectroscopy, and fluorescence microscopy measurements. The results show that this reaction is highly efficient, reversible, and mild and allows for immobilization of various sensitive functional groups. In addition, Langmuir-Blodgett lithography was used to generate structured SAMs. Site-selective immobilization of a fluorescent dye could be achieved by nitroxide exchange reactions.

• Fabrication of superhydrophobic polymer films with hierarchical silver microbowl array structures.

  Authors: Miaojun Xu, Nan Lu, Dianpeng Qi, Hongbo Xu, Yandong Wang, Shoulei Shi, Lifeng Chi

  Journal of colloid and interface science. 08/2011; 360(1):300-4.

  Flexible superhydrophobic polyvinyl alcohol (PVA) films with silver bowl-like array structure are fabricated based on the thermal evaporation with sphere monolayer as templates and the modificationFlexible superhydrophobic polyvinyl alcohol (PVA) films with silver bowl-like array structure are fabricated based on the thermal evaporation with sphere monolayer as templates and the modification of 1H, 1H, 2H, 2H-perfluorodecanethiol on silver surface. The silver microbowl arrays were composed of silver nanoparticles with an average diameter size of ca. 10 nm. The polymer films exhibit excellent stability and remarkable superhydrophobicity with a high water contact angle (CA) of about 163° and a low sliding angle (SA) of less than 3°.

• Fabrication of split-ring resonators by tilted nanoimprint lithography.

  Authors: Liguo Gao, Li Lin, Juanyuan Hao, Weifeng Wang, Renping Ma, Hongbo Xu, Jingsheng Yu, Nan Lu, Wenchong Wang, Lifeng Chi

  Journal of colloid and interface science. 08/2011; 360(1):320-3.

  An efficient fabrication technique for large area periodic metallic split-ring arrays has been demonstrated by the combination of tilted nanoimprint lithography and nanotransfer imprinting. TheAn efficient fabrication technique for large area periodic metallic split-ring arrays has been demonstrated by the combination of tilted nanoimprint lithography and nanotransfer imprinting. The feature size of the split-rings can be adjusted by varying the key geometry parameters of the original imprinting mold. Due to the flexible nature of PDMS molds, these arrays can be patterned on curved surfaces. The molds for nanoimprint lithography and nanotransfer imprinting can be used multiple times without a loss of fidelity.

• Cover Picture: A Nanosized Molybdenum Oxide Wheel with a Unique Electronic-Necklace Structure: STM Study with Submolecular Resolution (Angew. Chem. Int. Ed. 31/2011).

  Authors: Dingyong Zhong, Filipa Lourosa Sousa, Achim Müller, Lifeng Chi, Harald Fuchs

  Angewandte Chemie (International ed. in English). 07/2011; 50(31):6931.

• A nanosized molybdenum oxide wheel with a unique electronic-necklace structure: STM study with submolecular resolution.

  Authors: Dingyong Zhong, Filipa Lourosa Sousa, Achim Müller, Lifeng Chi, Harald Fuchs

  Angewandte Chemie (International ed. in English). 06/2011; 50(31):7018-21.

• Host-guest chemistry at interface for photoswitchable bioelectrocatalysis.

  Authors: Pengbo Wan, Yibo Xing, Yueyue Chen, Lifeng Chi, Xi Zhang

  Chemical communications (Cambridge, England). 06/2011; 47(21):5994-6.

  Photoswitchable bioelectrocatalysis of glucose with glucose oxidase in an "On-Off" state is fabricated from host-guest chemistry at an interface by using the photocontrolled reversible immobilizationPhotoswitchable bioelectrocatalysis of glucose with glucose oxidase in an "On-Off" state is fabricated from host-guest chemistry at an interface by using the photocontrolled reversible immobilization and detachment of ferrocene-labeled redox-polymer as mediator.

• Enhanced electrical conductivity of individual conducting polymer nanobelts.

  Authors: Lin Jiang, Yinghui Sun, Haiyang Peng, Lain-Jong Li, Tao Wu, Jan Ma, Freddy Yin Chiang Boey, Xiaodong Chen, Lifeng Chi

  Small (Weinheim an der Bergstrasse, Germany). 06/2011; 7(14):1949-53.

• Nanoscaled surface patterning of conducting polymers.

  Authors: Lin Jiang, Xing Wang, Lifeng Chi

  Small (Weinheim an der Bergstrasse, Germany). 05/2011; 7(10):1309-21.

  In continuing the steady development of integrated-circuit-related fabrication, the ability to pattern conducting polymers into smaller and smaller sizes in order to realize devices with enhancedIn continuing the steady development of integrated-circuit-related fabrication, the ability to pattern conducting polymers into smaller and smaller sizes in order to realize devices with enhanced performance or even wholly new properties begins to take a more prominent role in their advanced applications. This review summarizes the recent advances in top-down and bottom-up patterning of conducting polymers on surfaces with different approaches including direct writing, in-situ synthesis or assembly, etching, and nanoscratching. All of the latest emerging strategies have the potential to go beyond the current state of the art towards real progress in terms of high-precision positioning, high resolution, high throughout, higher stability, facile processing, and lower-cost production.

• High-resolution triple-color patterns based on the liquid behavior of organic molecules.

  Authors: Wenchong Wang, Chuan Du, Chenguang Wang, Michael Hirtz, Liqiang Li, Juanyuan Hao, Qiong Wu, Ran Lu, Nan Lu, Yue Wang, Harald Fuchs, Lifeng Chi

  Small (Weinheim an der Bergstrasse, Germany). 03/2011; 7(10):1403-6.

• Biomimetic antireflective hierarchical arrays.

  Authors: Hongbo Xu, Nan Lu, Gang Shi, Dianpeng Qi, Bingjie Yang, Haibo Li, Weiqing Xu, Lifeng Chi

  Langmuir : the ACS journal of surfaces and colloids. 03/2011; 27(8):4963-7.

  We report a simple method for the fabrication of biomimetic antireflective hierarchical arrays based on the combination of self-assembled polymer spheres and nanoimprint lithography (NIL). TheWe report a simple method for the fabrication of biomimetic antireflective hierarchical arrays based on the combination of self-assembled polymer spheres and nanoimprint lithography (NIL). The hierarchical structures are fabricated by creating nanopillars on the microscale round protrusion arrays, which are similar to natural mosquito eyes consisting of combined micro- and nanostructures. The hierarchical arrays dramatically suppress the surface reflection from visible to near-infrared regions with an angle of incidence of up to 70°.

• Two-dimensional self-assembly of linear molecular rods at the liquid/solid interface.

  Authors: Zhongcheng Mu, Lijin Shu, Harald Fuchs, Marcel Mayor, Lifeng Chi

  Langmuir : the ACS journal of surfaces and colloids. 02/2011; 27(4):1359-63.

  We report on the synthesis and scanning tunneling microscopy (STM) studies of a series of linear molecular rods (1-5) comprising different numbers and/or spatial arrangements of perfluorinatedWe report on the synthesis and scanning tunneling microscopy (STM) studies of a series of linear molecular rods (1-5) comprising different numbers and/or spatial arrangements of perfluorinated benzene and benzene subunits interlinked with diacetylenes in the para position and decorated with or without terminal dodecyl chains. The molecules organize themselves into well-ordered 2D crystal structures at the liquid/solid interface through intermolecular and molecule-substrate interactions. Whereas the molecules substituted by dodecyl chains form the lamellar structures with alternating rigid core rows and alkyl chain rows, the unsubstituted ones change the orientation of the rigid backbones with respect to the lamellar axis. The molecular arrangement is not influenced by fluoro substituents on any phenyl ring of the backbone, which suggests that the interactions between the π-conjugated backbones are dominated by close packing rather than by the dipole moments of the rods or fluorine-based intermolecular interactions.