Mao Li

Electrochemical-Coupling Layer-by-Layer (ECC–LbL) Assembly

Electrochemical-coupling layer-by-layer (ECC-LbL) assembly is introduced as a novel fabrication methodology for preparing layered thin films. This method allows us to covalently immobilize functional units (e.g., porphyrin, fullerene, and fluorene) into thin films having desired thicknesses and designable sequences for both homo- and heteroassemblies while ensuring efficient layer-to-layer electronic interactions. Films were prepared using a conventional electrochemical setup by a simple and inexpensive process from which various layering sequences can be obtained, and the photovoltaic functions of a prototype p/n heterojunction device were demonstrated.

Materials nanoarchitectonics for environmental remediation and sensing

The global environment has been variously compromised leading to problems such as global warming and radioactive contamination. In this feature article, we will focus especially on materials for environmental remediation based on the concept of materials nanoarchitectonics. The topics are classified into three categories: removal and degradation of toxic substances including waste due to fossil fuel usage and organic pollutants (continuously arising problems), current emerging topics concerning oil spills and nuclear waste (current urgent problems), and advanced methods based on supramolecular chemistry and nanotechnology (including breakthroughs for future development).

Paradigm shift from self-assembly to commanded assembly of functional materials: recent examples in porphyrin/fullerene supramolecular systems

Abstract Current nanotechnology based on top-down nanofabrication may encounter a variety of drawbacks in the near future so that development of alternative methods, including the so-called bottom-up approach, has attracted considerable attention. However, the bottom-up strategy, which often relies on spontaneous self-assembly, might be inefficient in the development of the requisite functional materials and systems. Therefore, assembly processes controlled by external stimuli might be a plausible strategy for the development of bottom-up nanotechnology. In this review, we demonstrate a paradigm shift from self-assembly to commanded assembly by describing several examples of assemblies of typical functional molecules, i.e. porphyrins and fullerenes. In the first section, we describe recent progress in the design and study of self-assembled and co-assembled supramolecular architectures of porphyrins and fullerenes. Then, we show examples of assembly induced by external stimuli. We emphasize the paradigm shift from self-assembly to commanded assembly by describing the recently developed electrochemical-coupling layer-by-layer (ECC-LbL) methodology.

In Situ Electrochemical Deposition and Doping of C60 Films Applied to High‐Performance Inverted Organic Photovoltaics

Novel C(60)-based cross-linked films formed by electrodeposition are produced and used as the electron-collection layer in inverted polymer solar cells (PSCs). The electrodeposited films exhibit a low work function of 4.2 eV and the PSCs perform well, with power conversion efficiencies of up to 6.31%. This new kind of electrodeposited film affords more opportunities to develop modified electrodes with a low work function.

In situ switching layer-by-layer assembly: one-pot rapid layer assembly via alternation of reductive and oxidative electropolymerization

In situ one-pot rapid layer-by-layer assembly of polymeric films as an active layer of a photoactive device via alternation of reductive and oxidative electropolymerization has been demonstrated. This novel fabrication without moving or changing experimental gears would be a powerful strategy to develop automated layer-by-layer machines.

Electrochemical Synthesis of Transparent, Amorphous, C60‐Rich, Photoactive, and Low‐Doped Film with an Interconnected Structure

© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Fullerene (C 60 ) is one of the most investigated species in energy and biological applications [ 1 , 2 ] due to its unique physicochemical properties of electrical conductivity [ 3 ] and electron defi ciency. [ 4 ] For practical applications, including in various electronic devices, preparation of high C 60 content Electrochemical Synthesis of Transparent, Amorphous, C 60 -Rich, Photoactive, and Low-Doped Film with an Interconnected Structure

SCATTER HOARDING AND HIPPOCAMPAL CELL PROLIFERATION IN SIBERIAN CHIPMUNKS

Food hoarding, especially scatter hoarding and retrieving food caches, requires spatial learning and memory and is an adaptive behavior important for an animals survival and reproductive success. In the present study, we examined the effects of hoarding behavior on cell proliferation and survival in the hippocampus of male and female Siberian chipmunks (Tamias sibiricus). We found that chipmunks in a semi-natural enclosure displayed hoarding behavior with large individual variations. Males ate more scatter-hoarded seeds than females. In addition, the display of hoarding behavior was associated with increased cell proliferation in the hippocampus and this increase occurred in a brain region-specific manner. These data provide further evidence to support the notion that new cells in the adult hippocampus are affected by learning and memory tasks and may play an important role in adaptive behavior.

Electrochemically Organized Isolated Fullerene-Rich Thin Films with Optical Limiting Properties

Electrochemical assembly was applied directly to determine the aggregation of nanoclusters in isolated fullerene-rich (54-63 wt %) thin films. The electroactive reactions were achieved using electroactive carbazole and pyrene, which led to distinguishable nanoparticle-like and irregular cluster formations. These films, with amorphous and transparent states, showed good photoactivity and significant optical limiting response with an excellent threshold of 63 mJ cm(-2). This work thus paves a way to assemble highly isolated (or monodispersed) building blocks into thin films at the molecular level with control of the nanostructural formations through important molecular design.

Hierarchical manipulation of uniform multi-nanoparticles by electrochemical coupling assembly

Assembling multiple nanomaterials into a single nanostructure is a promising way to obtain a multifunctionality derived from each building block. We address here the need for a general all-solution processed strategy to control the fabrication of multiple nanoparticles (NPs) at room temperature and under vacuum free conditions. The monodisperse multiple NPs were integrated successively into thin bulk-hybrid gradient or periodic tandem multilayer films through tuning the cycling number of cyclic voltammetry (CV), which are based on the quantitatively electrochemical deposition of each type of NPs thanks to the electrochemical coupling reaction of the N-alkylcarbazole ligand. This simple method yields nanoporous, transparent, stable and photoactive films with a hierarchical structure of multiple uniform NPs, exemplified by the prototype photodetector devices. Significantly, this strategy opens an avenue to fabricate low-cost wire and 3-dimensional NPs films on physically flexible conducting substrates.

Electroreductive Coupling Layer-by-Layer Assembly

Rapid and covalent layer-by-layer (LbL) assembly is of significance for practical applications because of superior chemical and mechanical stability. The electrochemical LbL assembly via an accelerating trigger can be automated and programmable in response to electrical signals to in situ fabricate covalently layered thin films with chemical and mechanical stability. In this paper, electroreductive coupling layer-by-layer assembly is introduced as both covalent and rapid methodology for preparing layered thin films. This assembly is triggered by C-C coupling of peripheral alkynyls, which have own absorption below 300 nm and can transform to optical and electrical inert double/single or triple/single alternative bonding formations significantly without optical or electric alternations of desirable photoelectric building blocks, superior to other linkers among covalent LbL assemblies. Not limited to fabrication of optical thin films, this assembly is readily available for oxygen sensitive substrates or materials and also a powerful addition to electrooxidative coupling LbL assembly for developing the economically dynamoelectric LbL machines without moving or changing experimental gears.