560 research outputs found
Recent advances in the formation of phase inversion membranes made from amorphous or semi-crystalline polymers
Structural characteristics in membranes formed by diffusion induced phase separation processes are discussed. Established theories on membrane formation from ternary systems can be extended to describe the effects of high or low molecular weight additives. A mechanism for the formation of nodular structures in the top layer of ultrafiltration membranes is presented. In the last part structures arising from polymer crystallization during immersion precipitation are discussed
Photovoltaic performance of an ultrasmall band gap polymer
A conjugated polymer (PBTTQ) that consists of alternating electron-rich bithiophene and electron-deficient thiadiazoloquinoxaline units was synthesized via Yamamoto polymerization with Ni(cod)(2) and provides a band gap of 0.94 eV. This represents one of the smallest band gaps obtained for a soluble conjugated polymer. When applied in a bulk heterojunction solar cell together with [84]PCBM as the electron acceptor, the polymer affords a response up to 1.3 mu m
Semiconducting Monolayer Materials as a Tunable Platform for Excitonic Solar Cells
The recent advent of two-dimensional monolayer materials with tunable
optoelectronic properties and high carrier mobility offers renewed
opportunities for efficient, ultra-thin excitonic solar cells alternative to
those based on conjugated polymer and small molecule donors. Using
first-principles density functional theory and many-body calculations, we
demonstrate that monolayers of hexagonal BN and graphene (CBN) combined with
commonly used acceptors such as PCBM fullerene or semiconducting carbon
nanotubes can provide excitonic solar cells with tunable absorber gap,
donor-acceptor interface band alignment, and power conversion efficiency, as
well as novel device architectures. For the case of CBN-PCBM devices, we
predict the limit of power conversion efficiencies to be in the 10 - 20% range
depending on the CBN monolayer structure. Our results demonstrate the
possibility of using monolayer materials in tunable, efficient, polymer-free
thin-film solar cells in which unexplored exciton and carrier transport regimes
are at play.Comment: 7 pages, 5 figure
Spatial modeling of the 3D morphology of hybrid polymer-ZnO solar cells, based on electron tomography data
A spatial stochastic model is developed which describes the 3D nanomorphology
of composite materials, being blends of two different (organic and inorganic)
solid phases. Such materials are used, for example, in photoactive layers of
hybrid polymer zinc oxide solar cells. The model is based on ideas from
stochastic geometry and spatial statistics. Its parameters are fitted to image
data gained by electron tomography (ET), where adaptive thresholding and
stochastic segmentation have been used to represent morphological features of
the considered ET data by unions of overlapping spheres. Their midpoints are
modeled by a stack of 2D point processes with a suitably chosen correlation
structure, whereas a moving-average procedure is used to add the radii of
spheres. The model is validated by comparing physically relevant
characteristics of real and simulated data, like the efficiency of exciton
quenching, which is important for the generation of charges and their transport
toward the electrodes.Comment: Published in at http://dx.doi.org/10.1214/11-AOAS468 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
The use of ZnO as optical spacer in polymer solar cells: Theoretical and experimental study
Binding hotspots of BAZ2B bromodomain: Histone interaction revealed by solution NMR driven docking.
Bromodomains are epigenetic reader domains, which have come under increasing scrutiny both from academic and pharmaceutical research groups. Effective targeting of the BAZ2B bromodomain by small molecule inhibitors has been recently reported, but no structural information is yet available on the interaction with its natural binding partner, acetylated histone H3K14ac. We have assigned the BAZ2B bromodomain and studied its interaction with H3K14ac acetylated peptides by NMR spectroscopy using both chemical shift perturbation (CSP) data and clean chemical exchange (CLEANEX-PM) NMR experiments. The latter was used to characterize water molecules known to play an important role in mediating interactions. Besides the anticipated Kac binding site, we consistently found the bromodomain BC loop as hotspots for the interaction. This information was used to create a data-driven model for the complex using HADDOCK. Our findings provide both structure and dynamics characterization that will be useful in the quest for potent and selective inhibitors to probe the function of the BAZ2B bromodomain.This is the final published version of the article. It has been published by the American Chemical Society in Biochemistry. The article can be accessed on their website here: http://pubs.acs.org/doi/abs/10.1021/bi500909d. It is freely available under a CC BY licence
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