Department of Materials and Interfaces

David Cahen, Head

Activities in the Department of Materials and Interfaces span range of topics from materials to energy research, nanoscience, and biomolecular systems. A UNIFYING THEME is the STUDY OF MATERIAL FUNCTIONALITY AND ITS RELATION TO FUNDAMENTAL PROPERTIES AT MULTIPLE SCALES. These properties may be mechanical, structural, electronic, and chemical. Some examples are: How do shapes and sizes of nm-sized particles affect their spectral properties? How can we tune the properties of solar cells by manipulating their surfaces? How does friction in knee and hip joints depend on the polyelectrolytes that lubricate them? How can we design self-assembling, even self-replicating chemical or biomolecular systems? THE RESEARCH IS BASED ON AN INTERDISCIPLINARY APPROACH, and indeed the scientists bring complementary experience in chemistry, physics, and biophysics, including theory and experiment.

Among the materials under active study we can note:

• nano-particles and nanotubes of carbon and inorganic materials
  
• composite materials down to the nanoscale, with unique mechanical properties
  
• nano-crystalline ceramics with unique combinations of electrical and mechanical properties;
  
• crystalline and non-crystalline pyroelectric and piezoelectric materials
  
• self-assembling supra-molecular architectures
  
• opto-electronic, pyroelectric, superconducting solids with extended bonding
  
• functionalized semiconductors and metals
  
• ultrathin ceramic or molecular organic films
  
• polymers and polyelectrolytes, complex fluids
  
• biomolecular materials: DNA, cytoskeleton
  
• biological tissues, cells, and matrix elasticity
  
• materials and processes for alternative, sustainable energy: electrochemical sequestration and recycling of atmospheric CO₂; photovoltaic (solar cell) materials and device structures

Experimental and theoretical approaches include:

• optical and X-ray photoelectron spectroscopies, Kelvin probe
  
• first-principles calculations, density functional theory
  
• inorganic synthesis, template synthesis, electrochemistry
  
• solid state impedance spectroscopy;
  
• surface force apparatus, atomic force microscopy, optical tweezers
  
• mechanical testing, elasticity & indentation
  
• crystal templating, chiral crystals, racemic separations
  
• X-ray diffraction & scattering
  
• advanced micro- & nanofabrication, including new (non-traditional) processes
  
• microfluidic devices
  
• advanced optical, electron, and X-ray microscopies
  
• in vitro reconstitution of functional biosystems, biomimetics
  
• theory of membranes and gels, charge interactions & elasticity
  
• application of theory to understanding biological cell & tissue properties.

Many facilities that we use are part of the Chemical Research Support Unit. They include the Electron Microscopy Unit, Surface Science (Scanning Probe Microscopies and Photoelectron Spectroscopy) unit, X-ray diffraction unit, combined clean rooms / micro-fabrication / biological specimen manipulation ("nano-bio") laboratories. Further facilities in the department or Chemical Support Services include systems for low temperature electrical transport and for optical and magnetic characterization of materials. In addition to new insights in how materials properties can be understood from their atomic, molecular, macro-/supra-molecular and over-all composition and structure, our inter- and multi-disciplinary strategy to the study of the functionality of materials and its relation to fundamental properties of matter at multiple scales, permits exploring new materials and combinations. It has also led to a number of practical applications.

R. Bar-Ziv

Artificial biochemical circuits

1.  Cell-free gene expression on a chip

2.  Cell-free expression of protein nano-structures

3.  Autonomous interrogation of the state of a living cell

The physics of microfluidic crystals

D. Cahen

Chemistry of Optoelectronic Materials and Devices - Molecule-controlled (opto)(bio)electronics

1.  Molecules as Electronic Conductors: Understanding the fundamentals, with L. Kronik, C. Sukenik (Bar Ilan), A.Kahn (Princeton), J. Gooding (UNSW), H, Zuilhof (Wageningen)

2.  Bio-opto-electronics: Electronic transport through proteins with M. Sheves, I. Pecht

Solar Energy: New materials concepts, basic understanding, micro-/nano-scopic studies of photovoltaics

1.  Molecular electronics for solar cells.

2.  How do nano- and poly-crystalline solar cells work? with G. Hodes, S. Cohen, K. Gartsman

3.  Optimizing the use of solar photons, with I. Lubomirsky, A. Zaban (Bar Ilan U)

M. Elbaum

Cellular Biophysics and Molecular Transport Machines

1.  Single-molecule manipulations using optical tweezers.

2.  Dynamics of DNA uptake into the cell nucleus.

3.  Structure and function of the nuclear pore complex (with Z. Reich): application of atomic force microscopy and advanced optical spectroscopies.

4.  Anomalous diffusion in polymer networks and living cells (with R. Granek).

5.  Organization of forces driving cell movements (with A. Bershadsky): optical force measurements and particle tracking studies; influence of cell biochemistry on biophysical forces.

6.  Novel surface-patterning lithographies.

G. Hodes

Semiconductor Films: preparation and properties

1.  Electrochemical and chemical bath deposition of semiconductor films.

2.  Nanocrystalline solar cells; semiconductor-sensitized nanoporous cells (with D. Cahen)

3.  Charge transfer in nanocrystalline films

E. Joselevich

Nanoscale Materials Chemistry and Biophysics;

Molecular Wires: From Self-Organization to Functional Nanosystems

1.  Organization of molecular wires and one-dimensional nanostructures

2.  Integration of molecular wires and one-dimensional nanostructures into functional nanosystems

3.  Characterization of molecular wires and one-dimensional nanostructures by mechanical and electrical measurements

J. Klein

Polymers, Complex Fluids, and Interfaces - Experimental studies of the behavior of confined simple and polymeric fluids.

1.  Confinement induced phase transitions

2.  Nanotribology

Surface-forces-measurement techniques at angstrom surface separations; polymers as molecular lubricants

1.  ATRP growth of polymers from surfaces

2.  Polyelectrolyte brushes

Molecular origins of biological lubrication Hydration lubrication: a new paradigm

1.  Properties of thin liquid films including aqueous electrolytes and polyelectrolytes.

2.  Hydrophobic interactions

3.  Slip at surfaces

4.  Boundary lubrication under water

5.  Tissue engineering and regenerative medicine: the role of lubrication

L. Kronik

Quantum Theory of Materials

1.  Unique properties of organic/inorganic interfaces

2.  Theory of novel magnetic materials

3.  Orbital-dependent functionals in density functional theory

4.  Real-space computational methodologies

I. Lubomirsky

Dielectric materials

1.  Properties of Ultra-Thin Self-Supported Crystalline Oxide Films.

2.  Infrared focal plane array based on freestanding pyroelectric films.

3.  Oxygen ion transport in thin freestanding films.

4.  High temperature, electrochemical CO₂ reduction

I. Rubinstein

Nanomaterials, Supramolecular chemistry, Sensors, Surface Chemistry, Electrochemistry

1.  Self-assembled supramolecular nanostructures on surfaces (with A. Vaskevich, H. Leader)

2.  Nanoparticle organization on surfaces using coordination layer-by-layer assembly (with A. Vaskevich, H. Leader)

3.  Plasmonic systems based on metal nano-island films prepared by evaporation/annealing (with A. Vaskevich)

4.  Application of metal nanoisland films in chemical and biological sensing using localized surface plasmon resonance spectroscopy (with A. Vaskevich)

5.  Chemical and electrochemical template synthesis in nanoporous membranes (with A. Vaskevich)

S. Safran

Soft Matter and Biomaterials

1.  Statistical physics of soft matter and biological physics (theory)

2.  Single cell physics and cell activity: cell shape, orientation, mechanics & polarization.

3.  Cooperative physics of cell activity: cell-surface interactions (adhesion), cell-cell elastic interactions.

4.  Inhomogeneous membranes, physics of inclusions in membranes: connection to lipid rafts.

5.  Membrane self-assembly of surfactants, lipids, and amphiphilic polymers.

6.  Electrostatic and fluctuation induced interactions in charged colloidal and membrane systems.

7.  Coupling of shape and shear elasticity in membranes and in biological cells.

J. Sagiv

Supramolecular Architecture at Interfaces (with R. Maoz)

1.  Supramolecular Surface Chemistry: Bottom-up Nanofabrication using Planned Self-Assembling Mono- and Multilayer Systems (with R. Maoz)

2.  Constructive Lithography: Contact Electrochemical Surface Patterning on Lateral Length Scales from Nanometer to Centimeter (with R. Maoz)

R. Tenne

Inorganic nanotubes and inorganic fullerene‐like materials: new materials with cage structure. From basic science to applications.

D. Wagner

Mechanics of Composite Materials and Carbon Nanotubes

1.  Micro- and nano-mechanics of tubes (C, WS₂)

2.  Electrospun polymer nanofibers

3.  LBL clay-films, and their composites

4.  Mechanics of biological composites (bone, dentin, cell adhesion)