Enzymatic Ligation Creates Discrete Multi-Nanoparticle Building Blocks for Self-Assembly

Enzymatic ligation of discrete nanoparticle?DNA conjugates creates nanoparticle dimer and trimer structures in which the nanoparticles are linked by single-stranded DNA, rather than double-stranded DNA as in previous experiments. Ligation is verified by agarose gel and small-angle X-ray scattering. This capability is utilized in two ways: first to create a new class of multiparticle building blocks for nanoscale self-assembly; second to develop a system which can amplify a population of discrete nanoparticle assemblies

Resist materials for 157-nm microlithography: an update

Fluorocarbon polymers and siloxane-based polymers have been identified as promising resist candidates for 157 nm material design because of their relatively high transparency at this wavelength. This paper reports our recent progress toward developing 157 nm resist materials based on the first of these two polymer systems. In addition to the 2-hydroxyhexafluoropropyl group, (alpha) -trifluoromethyl carboxylic acids have been identified as surprisingly transparent acidic functional groups. Polymers based on these groups have been prepared and preliminary imaging studies at 157 nm are described. 2-Trifluoromethyl-bicyclo[2,2,1] heptane-2-carboxylic acid methyl ester derived from methyl 2-(trifluoromethyl)acrylate was also prepared and gas-phase VUV measurements showed substantially improved transparency over norbornane. This appears to be a general characteristic of norbornane-bearing geminal electron-withdrawing substituents on the 2 carbon bridge. Unfortunately, neither the NiII nor PdII catalysts polymerize these transparent norbornene monomers by vinyl addition. However, several new approaches to incorporating these transparent monomers into functional polymers have been investigated. The first involved the synthesis of tricyclononene (TCN) monomers that move the bulky electron withdrawing groups further away from the site of addition. The hydrogenated geminally substituted TCN monomer still has far better transparency at 157 nm than norbornane. The second approach involved copolymerizing the norbornene monomers with carbon monoxide. The third approach involved free-radical polymerization of norbornene monomers with tetrafluoroethylene and/or other electron-deficient comonomers. All these approaches provided new materials with encouraging absorbance at 157 nm. The lithographic performance of some of these polymers is discussed

Resist materials for 157-nm microlithography: an update

Fluorocarbon polymers and siloxane-based polymers have been identified as promising resist candidates for 157 nm material design because of their relatively high transparency at this wavelength. This paper reports our recent progress toward developing 157 nm resist materials based on the first of these two polymer systems. In addition to the 2-hydroxyhexafluoropropyl group, (alpha) -trifluoromethyl carboxylic acids have been identified as surprisingly transparent acidic functional groups. Polymers based on these groups have been prepared and preliminary imaging studies at 157 nm are described. 2-Trifluoromethyl-bicyclo[2,2,1] heptane-2-carboxylic acid methyl ester derived from methyl 2-(trifluoromethyl)acrylate was also prepared and gas-phase VUV measurements showed substantially improved transparency over norbornane. This appears to be a general characteristic of norbornane-bearing geminal electron-withdrawing substituents on the 2 carbon bridge. Unfortunately, neither the NiII nor PdII catalysts polymerize these transparent norbornene monomers by vinyl addition. However, several new approaches to incorporating these transparent monomers into functional polymers have been investigated. The first involved the synthesis of tricyclononene (TCN) monomers that move the bulky electron withdrawing groups further away from the site of addition. The hydrogenated geminally substituted TCN monomer still has far better transparency at 157 nm than norbornane. The second approach involved copolymerizing the norbornene monomers with carbon monoxide. The third approach involved free-radical polymerization of norbornene monomers with tetrafluoroethylene and/or other electron-deficient comonomers. All these approaches provided new materials with encouraging absorbance at 157 nm. The lithographic performance of some of these polymers is discussed

Chemical modification of polystyrene under phase transfer catalysis

NRC publication: Ye

Organic Semiconductor-Containing Supramolecules: Effect of Small Molecule Crystallization and Molecular Packing

Small molecules (SMs) with unique optical or electronic properties provide an opportunity to incorporate functionality into block copolymer (BCP)-based supra-molecules. However, the assembly of supramolecules based on these highly crystalline molecules differs from their less crystalline counterparts. Here, two families of organic semiconductor SMs are investigated, where the composition of the crystalline core, the location (side- vs end-functionalizalion) of the alkyl solubilizing groups, and the constitution (branched vs linear) of the alkyl groups are varied. With these SMs, we present a systematic study of how the phase behavior of the SMs affects the overall assembly of these organic semiconductor -based supramolecules. The incorporation of SMs has a large effect on the interfacial curvature, the supramolecular periodicity, and the overall supramolecular morphology. The crystal packing of the SM within the supramolecule does not necessarily lead to the assembly of the comb block within the BCP microdomains, as is normally observed for alkyl-contaihing supramolecules. An unusual lamellar morphology with a wavy interface between the microdomains is observed due to changes in the packing structure of the small molecule within BCP microdomains. Since the supramolecular approach is modular and small molecules can be readily switched out, present studies provide useful guidance toward access supramolecular assemblies over several length scales using optically active and semiconducting small molecules

Bodipy-backboned polymers as electron donor in bulk heterojunction solar cells

Bodipy-based polymers, which possess a high absorption coefficient with a bandgap of similar to 1.6 eV, have been used as electron donor in solution-processed bulk heterojunction (BHJ) solar cells containing PCBM as acceptor. A power conversion efficiency (PCE) of similar to 2% has been achieved with V(oc) of similar to 0.8 eV and J(sc) of similar to 4.8 mA cm(-2)

Solution-Processable Crystalline Platinum-Acetylide Oligomers with Broadband Absorption for Photovoltaic Cells

A series of solution-processable and crystalline platinum-acetylide oligomers containing a thienyl benzothiadiazole thienyl core and oligothiophene alkynyl ligands are synthesized and characterized. X-ray crystallography analysis indicates a two-dimensional arrangement of oligomers through CH-pi interactions in single crystals. These oligomers show two intense and broad absorption bands in the visible spectral region, with the short-wavelength absorption band being strongly dependent on the olieothiophene length. In neat films, all the oligomers form large crystalline domains of several hundred nanometers in size upon thermal treatment and exhibit space-charge limited current (SCLC) mobilities on the order of 10(-5)-10(-4) cm(2) V(-1) s(-1). The photovoltaic properties of these oligomers were evaluated by fabricating bulk heterojunction devices with fullerene derivatives (PC(61)BM and PC(71)BM) and some of these devices showed high-power conversion efficiencies (PCEs) of up to 3% and a peak external quantum efficiency (EQE) to 50% under AM 1.5 simulated solar illumination. The present work suggests that well-defined platinum oligomers with desirable light-absorbing and self-assembly properties have potential for solution-processed organic photovoltaics