LIU, Bin

Assistant Professor

PhD (Chem) National University of Singapore, 2001
MSc & BSc (Chem) Nanjing University, 1998&1995

Contact information
Blk E5, 4 Engineering Drive 4, #02-17, Singapore 117576
Tel: (65) 6516 8049    Fax: (65) 6779 1936
Email: cheliub@nus.edu.sg

Postdoc (Chem. & Biochem.) University of California at Santa Barbara, 2003

RESEARCH

The overall research goal is to design, synthesize and characterize new materials with an emphasis on their applications in nano-biotechnology and clean energy. We are creating an active program of research which bridges areas of materials science, polymer chemistry, nano-science, bio-technology and device fabrication. Our current research is focused on developing functional conjugated polymers and seeking their applications in sensors and solar cells.

Synthesis of Functional Conjugated Polymers

Design and synthesis of functional conjugated polymers is the key component in our research. We mainly focus on the following three types of functional polymers: (1) Fluorescence turn on conjugated polymers with low fluorescence in aqueous solution, which increase their fluorescence upon interaction with targets (2) Conjugated polymers with multi-fluorescence properties, which response to analytes to yield different fluorescence signals for naked-eye detection (3) Conjugated polymers as hole-transporting materials for device fabrication.

Conjugated Polymer Based Nanobiosensors

Biosensors represent a most plausible and exciting application area for nanobiotechnology. Conjugated polymers (CPs) are ideally suited for sensing of biological entities due to their build in transduction mechanism afforded by the conjugated backbone. Our sensor research is directed at harnessing the unique properties of conjugated organic polymers (molecular wires effects). CPs serve as amplifiers (for signal amplification) or as reporters (for signal report) in homogenous bioassays have been demonstrated. Our strategy to develop CP based nano-biosensor is to create fluorescent CP nanoparticles with multicopies of the recognition elements covalently attached to their surface, which could trigger signal changes in the presence of the target.

Nanoscale Self-assembly of Conjugated Polyelectrolyte

Developing fluorescent core-shell or hollow-shell nanoparticles could lead to new applications for multilayers as optical and photonic components in devices, as indicators for drug delivery, and as catalytic microreactors. The most common luminescent colloidal structures have been constructed by infiltrating emissive polymers, polymer blends containing laser dyes, and semiconducting nanocrystals into the voids of these structures. A distinct disadvantage associated with this method is the inherent disruption or unpacking of active materials during infiltration which leads to decreased optical performance. Our research is to develop and evaluate functional fluorescent polymers and creates new coating technology to uniformly coat colloidal particles with functions such as electro-optic effects, biomedical properties and biosensor applications.

Conjugated Polymer based Dye Sensitized Solar Cells

Low fabrication cost and high device efficiency are the two main advantages for dye sensitized solar cells (DSSCs). However, most of the current devices require liquid electrolyte, which possess the problem of low stability for long term usage. To eliminate difficulties associate with liquid electrolyte, considerable research is devoted to the development of solid state dye sensitized solar cells. To fabricate solid state DSSCs with high efficiencies and meanwhile to reduce the cost, our strategy is to increase the surface area of metal oxide photoelectrodes, design p-type functional conjugated polymers with improved adsorption and penetration capabilities to porous electrode. We are also interested in assembling DSSCs on large area flexible substrates and investigating their interfacial structures and operation mechanisms. The ultimate goal is to develop efficient laminated flexible solar cells for commercial applications with simple processes.

SELECTED PUBLICATIONS

Rui Zhu, Changyun Jiang, Bin Liu* and Seeram Ramakrishna. "Highly Efficient Nanoporous TiO2-polythiophene Hybrid Solar Cells Based on Interfacial Modification Using A Metal-free Organic Dye". Adv. Mater. 2008, 10.1002/adma.200802388.

Zhen Fang, Kanyi Pu, and Bin Liu*. "Asymmetric Fluorescence Quenching of Dual-Emissive Porphyrin-Containing Conjugated Polyelectrolytes for Naked-Eye Mercury Ion Detection". Macromolecules 2008, 41(22), 8380-8387.

Kanyi Pu and Bin Liu*. "Conjugated Polyelectrolyte as Light-Up Macromolecular Probe for Heparin Sensing". Adv. Func. Mater. 2008, 10.1002/adfm.200800960.

Kanyi Pu and Bin Liu*. "A multicolor cationic Conjugated Polymer for Naked-eye Detection and Quantification of Heparin". Macromolecules 2008, 41(18), 6636-6640.

Xizhe Liu, Rui Zhu, Yong Zhang, Bin Liu* and Seeram Ramakrishna. "Anionic Benzothiadiazole Containing Polyfluorene and Oligofluorene as Organic Sensitizers for Dye-sensitized Solar Cells". Chem. Commun. 2008, 32, 3789-3791.

Kanyi Pu and Bin Liu*. "Optimizing the Cationic Conjugated Polymer Sensitized Fluorescent Signal of Dye Labeled Oligonucleotide for Biosensor Applications. Biosensors and Bioelectronics". 2008, DOI:10.1016/j.bios.2008.07.029.

Kanyi Pu, Zhen Fang and Bin Liu*. "Effect of Charge Density on Energy Transfer Properties of Cationic Conjugated Polymers". Adv. Funct. Mater. 2008, 18(8), 1321-1328.

Rui Zhu, Changyun Jiang, Xizhe Liu, Bin Liu*, Abhishek Kumar, Seeram Ramakrishna. "Improved Adhesion of Interconnected TiO2 Nanofiber Network on Conductive Substrate and Its Application in Polymer Photovoltaic Devices". Appl. Phys. Lett. 2008, 93(10), 13102-13105.

Jing Wang and Bin Liu*. "Highly Sensitive and Selective Detection of Hg2+ in Aqueous Solution with Mercury Specific DNA and Sybr Green" I. Chem. Commun. 2008, 4759-4761.