Karen K. Gleason

Direct Monolithic Integration of Organic Photovoltaic Circuits on Unmodified Paper

There has been signifi cant recent interest in integrating electronics into low-cost paper substrates, including transistors, storage devices, displays, and circuitry. [ 1–4 ] Paper-based photovoltaics (PVs) could serve as an “on-chip” power source for these paper electronics, and also create attractive new paradigms for solar power distribution, including seamless integration into ubiquitous formats such as window shades, wall coverings, apparel, and documents. Module installation may be as simple as cutting paper to size with scissors or tearing it by hand and then stapling it to roof structures or gluing it onto walls. Moreover, paper is ∼ 1000 times less expensive ( ∼ 0.01

Polymer‐Free Near‐Infrared Photovoltaics with Single Chirality (6,5) Semiconducting Carbon Nanotube Active Layers

· m − 2 ) than traditional glass substrates ( ∼ 10

CVD of polymeric thin films: applications in sensors, biotechnology, microelectronics/organic electronics, microfluidics, MEMS, composites and membranes

· m − 2 ) [ 5 , 6 ]

Identification of defects and impurities in chemical‐vapor‐deposited diamond through infrared spectroscopy

We demonstrate a polymer-free carbon-based photovoltaic device that relies on exciton dissociation at the SWNT/C(60) interface, as shown in the figure. Through the construction of a carbon-based photovoltaic completely free of polymeric active or transport layers, we show both the feasibility of this novel device as well as inform the mechanisms for inefficiencies in SWNTs and carbon based solar cells.

Growth of fluorocarbon polymer thin films with high CF2 fractions and low dangling bond concentrations by thermal chemical vapor deposition

Polymers with their tunable functionalities offer the ability to rationally design micro- and nano-engineered materials. Their synthesis as thin films have significant advantages due to the reduced amounts of materials used, faster processing times and the ability to modify the surface while preserving the structural properties of the bulk. Furthermore, their low cost, ease of fabrication and the ability to be easily integrated into processing lines, make them attractive alternatives to their inorganic thin film counterparts. Chemical vapor deposition (CVD) as a polymer thin-film deposition technique offers a versatile platform for fabrication of a wide range of polymer thin films preserving all the functionalities. Solventless, vapor-phase deposition enable the integration of polymer thin films or nanostructures into micro- and nanodevices for improved performance. In this review, CVD of functional polymer thin films and the polymerization mechanisms are introduced. The properties of the polymer thin films that determine their behavior are discussed and their technological advances and applications are reviewed.

FLEXIBLE FLUOROCARBON WIRE COATINGS BY PULSED PLASMA ENHANCED CHEMICAL VAPOR DEPOSITION

Hydrogen‐, oxygen‐, and nitrogen‐related defects in chemical‐vapor‐deposited (CVD) diamond have been observed by infrared spectroscopy and found to affect optical absorptions in spectral regions of commercial interest. The origin of absorptions in the infrared spectrum at 2820 and 2833 cm−1, which have been observed previously without being understood, have been assigned. The presence of these absorptions and the evidence of oxygen and nitrogen incorporation in CVD diamond have important implications for both the design of CVD diamond growth systems and the design of processes involving oxygen addition. In films which contain high hydrogen concentrations (≳0.2 at. %), some evidence has been found indicating the presence of a hydrogen environment, not present in films with lower hydrogen contents, which may be related to sp2‐bonded carbon.

Polymeric Nanopore Membranes for Hydrophobicity-Based Separations by Conformal Initiated Chemical Vapor Deposition

Thermal chemical vapor deposition was used to deposit fluorocarbon films with chemical resemblance to bulk polytetrafluoroethylene. X‐ray photoelectron spectroscopy revealed that the films deposited from thermal decomposition of hexafluoropropylene oxide had fluorine to carbon ratios of 2.0 and CF2 fractions of 90% along with 10% of CF3 and CF moieties. Electron spin resonance results found the dangling bond density to be 1.2×1018 spins/cm3, low compared to conventional plasma polymerized films. Low dangling bond densities were achieved by using a clean source of CF2 in the absence of plasma source.

Patterning Nanodomains with Orthogonal Functionalities: Solventless Synthesis of Self-Sorting Surfaces

A method to coat thin wires, 25 μm in diameter, with fluorocarbon material that is flexible and conformal has been achieved using pulsed plasma enhanced chemical vapor deposition (PECVD). This process enables the chemical composition of the films to be tailored in order to achieve similar stoichiometry and chemical composition to bulk polytetrafluoroethylene [PTFE, (CF2)n, Teflon™]. The deposited film had a F/C ratio of 1.9 and a CF2 fraction of 65%. In comparison, a film deposited under continuously applied power had a F/C ratio of only 1.6 and a CF2 fraction of 32% and was found to form brittle wire coatings. The flexibility of the pulsed PECVD film was consistent with its connectivity number of 2.1 corresponding to an underconstrained, flexible material. In addition, the connectivity number for the brittle film was 2.5, consistent with an overconstrained brittle network.

Stable Dropwise Condensation for Enhancing Heat Transfer via the Initiated Chemical Vapor Deposition (iCVD) of Grafted Polymer Films

High-aspect ratio hydrophobic, cylindrical nanopores having diameters as low as 5 nm are rapidly fabricated using conformal vapor deposition of fluorinated polymeric layers into porous track-etched polycarbonate membranes. The resultant selectivity of these membranes for pairs of small molecules of similar size, but of different hydrophobicity, arises from solute-pore wall interactions emphasized by confinement. Increasing selectivity was observed as pore diameter decreased and as the surface of the pore became more hydrophobic. Cylindrical pores provided higher selectivity than bottleneck-shaped pores having the same minimum diameter. A maximum selectivity of 234 was achieved between mesitylene and phloroglucinol by the best performing membrane. Membranes with small fluorinated pores exhibited an effective cutoff based on the polar surface area of the molecules, with limited correlation with solute size. This technology could lead to a new generation of membrane separations based on specific interactions.

Deterministic Order in Surface Micro-Topologies through Sequential Wrinkling

Vapor deposited functional polymer thin films can undergo rapid covalent functionalization. Patterning of two functional layers displaying orthogonal reactivity enables sorting of aqueous mixtures of dyes and nanoparticles, such as quantum dots, onto selective areas of nanopatterned surfaces.