Absence of Structural Impact of Noble Nanoparticles on P3HT: PCBM Blends for Plasmon Enhanced Bulk-Heterojunction Organic Solar Cells Probed by Synchrotron Grazing Incidence X-Ray Diffraction

The incorporation of noble metal nanoparticles, displaying localized surface plasmon resonance, in the active area of donor-acceptor bulk-heterojunction organic photovoltaic devices is an industrially compatible light trapping strategy, able to guarantee better absorption of the incident photons and give an efficiency improvement between 12% and 38%. In the present work, we investigate the effect of Au and Ag nanoparticles blended with P3HT: PCBM on the P3HT crystallization dynamics by synchrotron grazing incidence X-ray diffraction. We conclude that the presence of (1) 80nm Au, (2) mix of 5nm, 50nm, 80nm Au, (3) 40nm Ag, and (4) 10nm, 40nm, 60nm Ag colloidal nanoparticles, at different concentrations below 0.3 wt% in P3HT: PCBM blends, does not affect the behaviour of the blends themselves

Initial stages of molecular-beam epitaxy growth of GaN on 6H-SiC(0001)

We studied the atomic H etching of 6H-SiC substrates and the initial stages of GaN/6H-SiC molecular-beam epitaxy growth. Atomic H etched 6H-SiC(0001)Si and (000math)C surfaces show a (√×√)−R30° and a (1×1) reconstruction respectively, with 0.7±0.2 monolayers of remnant O on both surfaces. GaN/6H-SiC(0001)Si growth is initiated by the formation of islands that develop into flat-top terraces through coalescence. Growth steps of one or integer numbers of the GaN atomic bilayer height are observed. GaN grown on 6H-SiC(000math)C is rougher with islands of irregular shape. X-ray photoemission spectroscopy studies show that Si 2p and C 1s photoelectron inelastic mean free paths in GaN are 22±1 and 20±1 Å, respectively

Bias stability of solution-processed In2O3 thin film transistors

We report the effect of bias stress on the drain current and threshold voltage of n-channel thin-film transistors based on solution processed In2O3 layers. Application of a positive gate bias for variable time-periods led to displacements of the transfer curves in the positive gate bias direction. On switching off the gate bias, the transfer curves returned close to their pre-stress state on a timescale similar to that when the gate bias was switched on. The time dependence of the threshold voltage shift is described well by a stretched-exponential model. The temporal behaviour of the threshold voltage shifts is consistent with charge trapping as the dominant effect, although some defect formation cannot be ruled out

Influence of solvent polarity on the structure of drop-cast electroactive tetra(aniline)-surfactant thin films

The structure of drop-cast thin films of an electroactive oligomer–surfactant complex can be tuned through variation of solvent polarity.</p

Nondestructive Method for Mapping Metal Contact Diffusion in In2O3 Thin-Film Transistors

The channel width-to-length ratio is an important transistor parameter for integrated circuit design. Contact diffusion into the channel during fabrication or operation alters the channel width and this important parameter. A novel methodology combining atomic force microscopy and scanning Kelvin probe microscopy (SKPM) with self-consistent modeling is developed for the nondestructive detection of contact diffusion on active devices. Scans of the surface potential are modeled using physically based Technology Computer Aided Design (TCAD) simulations when the transistor terminals are grounded and under biased conditions. The simulations also incorporate the tip geometry to investigate its effect on the measurements due to electrostatic tip–sample interactions. The method is particularly useful for semiconductor– and metal–semiconductor interfaces where the potential contrast resulting from dopant diffusion is below that usually detectable with scanning probe microscopy

X-ray reflectivity of an Sb delta-doping layer in silicon

X‐ray reflectivity measurements were made on Si(001) crystals containing a delta‐doping layer of Sb atoms a few nanometers below the surface. The measurements show the Sb doping profile to be abrupt towards the substrate side of the sample and to decay towards the surface with a characteristic decay length of 1.01 nm

Site-specific protein photochemical covalent attachment to carbon nanotube side walls and its electronic impact on single molecule function

Functional integration of proteins with carbon-based nanomaterials such as nanotubes holds great promise in emerging electronic and optoelectronic applications. Control over protein attachment poses a major challenge for consistent and useful device fabrication, especially when utilizing single/few molecule properties. Here, we exploit genetically encoded phenyl azide photochemistry to define the direct covalent attachment of four different proteins, including the fluorescent protein GFP and a β-lactamase binding protein (BBP), to carbon nanotube side walls. AFM showed that on attachment BBP could still recognize and bind additional protein components. Single molecule fluorescence revealed that on attachment to SWCNTs function was retained and there was feedback to GFP in terms of fluorescence intensity and improved resistance to photobleaching; GFP is fluorescent for much longer on attachment. The site of attachment proved important in terms of electronic impact on GFP function, with the attachment site furthest from the chromophore having the larger effect on fluorescence. Our approach provides a versatile and general method for generating intimate protein–CNT hybrid bioconjugates. It can be potentially applied to any protein of choice; the attachment position and thus interface characteristics with the CNT can easily be changed by simply placing the phenyl azide chemistry at different residues by gene mutagenesis. Thus, our approach will allow consistent construction and modulate functional coupling through changing the protein attachment position

Functional modulation and directed assembly of an enzyme through designed non-natural post-translation modification

Post-translational modification (PTM) modulates and supplements protein functionality. In nature this high precision event requires specific motifs and/or associated modification machinery. To overcome the inherent complexity that hinders PTM's wider use, we have utilized a non-native biocompatible Click chemistry approach to site-specifically modify TEM β-lactamase that adds new functionality. In silico modelling was used to design TEM β-lactamase variants with the non-natural amino acid p-azido-L-phenylalanine (azF) placed at functionally strategic positions permitting residue-specific modification with alkyne adducts by exploiting strain-promoted azide–alkyne cycloaddition. Three designs were implemented so that the modification would: (i) inhibit TEM activity (Y105azF); (ii) restore activity compromised by the initial mutation (P174azF); (iii) facilitate assembly on pristine graphene (W165azF). A dibenzylcyclooctyne (DBCO) with amine functionality was enough to modulate enzymatic activity. Modification of TEMW165azF with a DBCO–pyrene adduct had little effect on activity despite the modification site being close to a key catalytic residue but allowed directed assembly of the enzyme on graphene, potentially facilitating the construction of protein-gated carbon transistor system