A5029685348- Block Copolymer Self-Assembly
- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Advanced Polymer Synthesis and Characterization
- Perovskite Materials and Applications
- Pickering emulsions and particle stabilization
- Polymer Surface Interaction Studies
- Surfactants and Colloidal Systems
- Polymer crystallization and properties
- Material Dynamics and Properties
- Anodic Oxide Films and Nanostructures
- Theoretical and Computational Physics
- Synthesis and properties of polymers
- Fluid Dynamics and Thin Films
- Polymer Nanocomposites and Properties
- Rheology and Fluid Dynamics Studies
- Force Microscopy Techniques and Applications
- Machine Learning in Materials Science
- Surface Modification and Superhydrophobicity
- Quantum Dots Synthesis And Properties
- Micro and Nano Robotics
- Advanced Sensor and Energy Harvesting Materials
- Nanofabrication and Lithography Techniques
- Energetic Materials and Combustion
- Particle physics theoretical and experimental studies
John Brown University
2024-2025
Lawrence Berkeley National Laboratory
2016-2025
University of Massachusetts Amherst
2016-2025
Brown University
1976-2025
Tohoku University
2015-2024
University of Massachusetts Boston
1996-2024
Advanced Institute of Materials Science
2013-2024
Cyclotron (Netherlands)
2024
Emory University
2017-2024
Ministry of Fisheries and Marine Resource Development
2024
The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous electrical, optical, or mechanical properties. Recent advances reveal routes to exploit both enthalpic entropic interactions so as direct the spatial distribution thereby control macroscopic performance material. For example, by tailoring particle coating size, researchers have created self-healing materials improved sustainability self-corralling rods photovoltaic...
We show a simple, robust, chemical route to the fabrication of ultrahigh-density arrays nanopores with high aspect ratios using equilibrium self-assembled morphology asymmetric diblock copolymers. The dimensions and lateral density array are determined by segmental interactions copolymer molecular weight. Through direct current electrodeposition, we fabricated vertical nanowires densities in excess 1.9 x 10(11) wires per square centimeter. found markedly enhanced coercivities ferromagnetic...
A simple technique for precisely controlling the interfacial energies and wetting behavior of polymers in contact with solid surfaces is described. End-functionalized statistical random copolymers styrene methylmethacrylate were synthesized, fraction f varying from 0 to 1, end-grafted onto silicon substrates create copolymer brushes about 5 nanometers thick. For < 0.7, polystyrene (PS) films (20 thick) rapidly dewet when heated well above glass transition temperature. The angle resulting...
The self-assembly of particles at fluid interfaces, driven by the reduction in interfacial energy, is well established. However, for nanoscopic particles, thermal fluctuations compete with energy and give rise to a particle-size-dependent self-assembly. Ligand-stabilized nanoparticles assembled into three-dimensional constructs fluid-fluid where properties unique were preserved. small size led weak confinement interface that opens avenues size-selective particle assembly, two-dimensional...
The preparation of a wide variety unique polymer brush structures can be accomplished by "living" free radical polymerization vinyl monomers from surface-tethered alkoxyamines or tethered α-halo esters in the presence (PPh3)2NiBr2. use process permits molecular weight and polydispersity covalently attached chains to accurately controlled while also allowing formation block copolymers sequential growth surface. These random copolymer brushes have been used control surface properties.
A series of acceptor-donor-acceptor simple oligomer-like small molecules based on oligothiophenes, namely, DRCN4T-DRCN9T, were designed and synthesized. Their optical, electrical, thermal properties photovoltaic performances systematically investigated. Except for DRCN4T, excellent obtained DRCN5T-DRCN9T. The devices DRCN5T, DRCN7T, DRCN9T with axisymmetric chemical structures exhibit much higher short-circuit current densities than those DRCN6T DRCN8T centrosymmetric structures, which is...
Local control of the domain orientation in diblock copolymer thin films can be obtained by application electric fields on micrometer-length scales. Thin an asymmetric polystyrene-polymethylmethacrylate copolymer, with cylindrical polymethylmethacrylate microdomains, were spin-coated onto substrates previously patterned planar electrodes. The substrates, 100-nanometer-thick silicon nitride membranes, allow direct observation electrodes and structure transmission electron microscopy. cylinders...
Generating laterally ordered, ultradense, macroscopic arrays of nanoscopic elements will revolutionize the microelectronic and storage industries. We used faceted surfaces commercially available sapphire wafers to guide self-assembly block copolymer microdomains into oriented with quasi–long-range crystalline order over arbitrarily large wafer surfaces. Ordered cylindrical 3 nanometers in diameter, areal densities excess 10 terabits per square inch, were produced. The sawtoothed substrate...
Abstract The self‐asembly of block copolymers is a promising platform for the “bottom‐up” fabrication nanostructured materials and devices. This review covers some advances made in this field from laboratory setting to applications where are use.
This work investigated the thermoelectric properties of thin silicon membranes that have been decorated with high density nanoscopic holes. These "holey silicon" (HS) structures were fabricated by either nanosphere or block-copolymer lithography, both which are scalable for practical device application. By reducing pitch hexagonal holey pattern down to 55 nm 35% porosity, thermal conductivity HS is consistently reduced 2 orders magnitude and approaches amorphous limit. With a ZT value ∼0.4...
Controlling thin film morphology is key in optimizing the efficiency of polymer-based photovoltaic (PV) devices. We show that and interfacial behavior multicomponent active layers confined between electrodes are strongly influenced by preparation conditions. Here, we provide detailed descriptions morphologies mixtures regioregular poly(3-hexylthiophene) (P3HT) [6,6]-phenyl C61-butyric acid methyl ester (PCBM), a typical layer PV device, contact with an anode PEDOT-PSS either unconfined or Al...
Abstract The chemical structure of donors and acceptors limit the power conversion efficiencies achievable with active layers binary donor-acceptor mixtures. Here, using quaternary blends, double cascading energy level alignment in bulk heterojunction organic photovoltaic are realized, enabling efficient carrier splitting transport. Numerous avenues to optimize light absorption, transport, charge-transfer state levels opened by constitution components. Record-breaking PCEs 18.07% achieved...
A double-layered nanoporous membrane suitable for virus filtration has been fabricated. The top layer cylindrical pores with diameters of 15 nm and a narrow pore size distribution (see figure). bottom support is conventional microfiltration membrane. This asymmetric completely blocks human rhinovirus type 14 (colored green) from penetrating into pores, while proteins such as bovine serum albumin yellow) freely pass through the pores.
Interfacial interactions underpin phenomena ranging from adhesion to surface wetting. Here, we describe a simple, rapid, and robust approach modifying solid surfaces, based on an ultrathin cross-linkable film of random copolymer, which does not rely specific chemistries. Specifically, thin films benzocyclobutene-functionalized copolymers styrene methyl methacrylate were spin coated or transferred, then thermally cross-linked wide variety metal, metal oxide, semiconductor, polymeric producing...
Synthetic polymers offer a wealth of opportunities to design responsive materials triggered by external stimuli. Changing the length, chemical composition, architecture, and topology chains allows response mechanisms rates be easily manipulated; devices based on entropy chains, surface energies, specific segmental interactions can readily made. Although numerous applications exist, intriguing possibilities are emerging that have tremendous potential further developments in surface-responsive...
A freely floating polymer film, tens of nanometers in thickness, wrinkles under the capillary force exerted by a drop water placed on its surface. The wrinkling pattern is characterized number and length wrinkles. dependence elastic properties film confirms recent theoretical predictions selection with well-defined scale instability. We combined scaling relations that were developed for those to construct metrology measuring elasticity thickness ultrathin films relies no more than dish fluid...
Abstract Most nonfullerene acceptors developed so far for high‐performance organic solar cells (OSCs) are designed in planar molecular geometry containing a fused‐ring core. In this work, new acceptor of DF‐PCIC is synthesized with an unfused‐ring core two cyclopentadithiophene (CPDT) moieties and one 2,5‐difluorobenzene (DFB) group. A nearly realized through the F···H noncovalent interaction between CPDT DFB DF‐PCIC. After proper optimizations, OSCs as polymer PBDB‐T donor yield best power...
Neutron reflectivity from annealed thin films of the poly(styrene-b-deuterated methylmethacrylate), P(S-b-D-MMA), reveals formation a multilayered morphology parallel to film surface. This multilayer forms so that PS locates, preferentially, at air/copolymer and D-PMMA substrate/copolymer interfaces with layer thicknesses these one-half found in bulk. P(D-S-b-MMA) lower molecular weight shows first evidence surface-induced ordering copolymers phase mixed state characterized by an...
We designed and synthesized the DPPEZnP-TEH molecule, with a porphyrin ring linked to two diketopyrrolopyrrole units by ethynylene bridges. The resulting material exhibits very low energy band gap of 1.37 eV broad light absorption 907 nm. An open-circuit voltage 0.78 V was obtained in bulk heterojunction (BHJ) organic solar cells, showing loss only 0.59 eV, which is first report that small molecule cells show losses <0.6 eV. optimized remarkable external quantum efficiency, short circuit...