scholarly journals Oligodimethylsiloxane-Oligoproline Block Co-Oligomers: the Interplay between Aggregation and Phase Segregation in Bulk and Solution

2021 ◽  
Vol 143 (10) ◽  
pp. 4032-4042
Author(s):  
Brigitte A.G. Lamers ◽  
Andreas Herdlitschka ◽  
Tobias Schnitzer ◽  
Mathijs F.J. Mabesoone ◽  
Sandra M.C. Schoenmakers ◽  
...  
Keyword(s):  
Phase Segregation

Nanostructured Polymer Brushes With Reversibly Changing Properties

2002 ◽  
Vol 727 ◽  
Author(s):  
Denys Usov ◽  
Manfred Stamm ◽  
Sergiy Minko ◽  
Christian Froeck ◽  
Andreas Scholl ◽  
...  
Keyword(s):  
Polymer Brushes ◽  
Phase Segregation ◽  
Water Contact ◽  
Angle Measurements ◽  
Nanostructured Polymer ◽  
Contact Angle Measurements ◽  
Vertical Segregation ◽  
Oxygen Plasma Etching ◽  
Grafting From ◽  
Photoemission Electron

AbstractWe investigated the interplay between different mechanisms of the lateral and vertical segregation in the synthesized via “grafting from” approach symmetric A/B (where A and B are poly(styrene-co-2,3,4,5,6-pentafluorostyrene) and poly(methylmethacrylate), respectively) polymer brushes upon exposure to different solvents. We used X-ray photoemission electron spectroscopy and microscopy (X-PEEM), AFM, water contact angle measurements, and oxygen plasma etching to study morphology of the brushes. The ripple morphology after toluene (nonselective solvent) revealed elongated lamellar-like domains of A and B polymers alternating across the surface. The dimple-A morphology consisting of round clusters of the polymer A was observed after acetone (selective solvent for B). The top layer was enriched with the polymer B showing that the brush underwent both the lateral and vertical phase segregation. A qualitative agreement with predictions of SCF theory was found.

scholarly journals Influence of the Active Layer Structure on the Photovoltaic Performance of Water-Soluble Polythiophene-Based Solar Cells

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1640
Author(s):  
Massimiliano Lanzi ◽  
Debora Quadretti ◽  
Martina Marinelli ◽  
Yasamin Ziai ◽  
Elisabetta Salatelli ◽  
...  
Keyword(s):  
Solar Cells ◽  
Layer Structure ◽  
Photovoltaic Performance ◽  
Phase Segregation ◽  
Water Soluble ◽  
Polymerization Reaction ◽  
Fullerene Derivative ◽  
C60 Fullerene ◽  
Photovoltaic Efficiency ◽  
Single Material

A new side-chain C60-fullerene functionalized thiophene copolymer bearing tributylphosphine-substituted hexylic lateral groups was successfully synthesized by means of a fast and effective post-polymerization reaction on a regioregular ω-alkylbrominated polymeric precursor. The growth of the polymeric intermediate was followed by NMR spectrometry in order to determine the most convenient reaction time. The obtained copolymer was soluble in water and polar solvents and was used as a photoactive layer in single-material organic photovoltaic (OPV) solar cells. The copolymer photovoltaic efficiency was compared with that of an OPV cell containing a water-soluble polythiophenic homopolymer, functionalized with the same tributylphosphine-substituted hexylic side chains, in a blend with a water-soluble C60-fullerene derivative. The use of a water-soluble double-cable copolymer made it possible to enhance the control on the nanomorphology of the active blend, thus reducing phase-segregation phenomena, as well as the macroscale separation between the electron acceptor and donor components. Indeed, the power conversion efficiency of OPV cells based on a single material was higher than that obtained with the classical architecture, involving the presence of two distinct ED and EA materials (PCE: 3.11% vs. 2.29%, respectively). Moreover, the synthetic procedure adopted to obtain single material-based cells is more straightforward and easier than that used for the preparation of the homopolymer-based BHJ solar cell, thus making it possible to completely avoid the long synthetic pathway which is required to prepare water-soluble fullerene derivatives.

Stabilizing Mixed Halide Lead Perovskites against Photoinduced Phase Segregation by A-Site Cation Alloying

2021 ◽  
Vol 6 (3) ◽  
pp. 837-847
Author(s):  
Pronoy Nandi ◽  
Zijia Li ◽  
Younghoon Kim ◽  
Tae Kyu Ahn ◽  
Nam-Gyu Park ◽  
...  
Keyword(s):  
Phase Segregation ◽  
A Site

scholarly journals Size-Dependent Alloying Ability of Immiscible W-Cu Bimetallic Nanoparticles: A Theoretical and Experimental Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1047
Author(s):  
Hongbo Zhang ◽  
Tao Liu ◽  
Siqi Zhao ◽  
Zhanyuan Xu ◽  
Yaozha Lv ◽  
...  
Keyword(s):  
Binary Systems ◽  
Bimetallic Nanoparticles ◽  
Driving Forces ◽  
Phase Particle ◽  
Phase Segregation ◽  
High Yield ◽  
Universal Method ◽  
Face Centered Cubic ◽  
Original Size ◽  
Face Centered

The preparation of alloyed bimetallic nanoparticles (BNPs) between immiscible elements is always a huge challenge due to the lack of thermodynamic driving forces. W–Cu is a typical immiscible binary system, and it is difficult to alloy them under conventional circumstances. Here, we used the bond energy model (BEM) to calculate the effect of size on the alloying ability of W–Cu systems. The prediction results show that reducing the synthesis size (the original size of W and Cu) to less than 10 nm can obtain alloyed W–Cu BNPs. Moreover, we prepared alloyed W50Cu50 BNPs with a face-centered-cubic (FCC) crystalline structure via the nano in situ composite method. Energy-dispersive X-ray spectroscopy (EDS) coupled with scan transmission electron microscopy (STEM) confirmed that W and Cu are well mixed in a single-phase particle, instead of a phase segregation into a core-shell or other heterostructures. The present results suggest that the nanoscale size effect can overcome the immiscibility in immiscible binary systems. In the meantime, this work provided a high-yield and universal method for preparing alloyed BNPs between immiscible elements.

scholarly journals Non-isothermal phase-field simulations of laser-written in-plane SiGe heterostructures for photonic applications

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ozan Aktas ◽  
Yuji Yamamoto ◽  
Mehmet Kaynak ◽  
Anna C. Peacock
Keyword(s):  
Quantum Wells ◽  
Phase Field ◽  
Silicon Germanium ◽  
Phase Segregation ◽  
Layer By Layer ◽  
Beam Position ◽  
Graded Index ◽  
Semiconductor Alloy ◽  
Scan Speed ◽  
Growth Methods

AbstractAdvanced solid-state devices, including lasers and modulators, require semiconductor heterostructures for nanoscale engineering of the electronic bandgap and refractive index. However, existing epitaxial growth methods are limited to fabrication of vertical heterostructures grown layer by layer. Here, we report the use of finite-element-method-based phase-field modelling with thermocapillary convection to investigate laser inscription of in-plane heterostructures within silicon-germanium films. The modelling is supported by experimental work using epitaxially-grown Si0.5Ge0.5 layers. The phase-field simulations reveal that various in-plane heterostructures with single or periodic interfaces can be fabricated by controlling phase segregation through modulation of the scan speed, power, and beam position. Optical simulations are used to demonstrate the potential for two devices: graded-index waveguides with Ge-rich (>70%) cores, and waveguide Bragg gratings with nanoscale periods (100–500 nm). Periodic heterostructure formation via sub-millisecond modulation of the laser parameters opens a route for post-growth fabrication of in-plane quantum wells and superlattices in semiconductor alloy films.

scholarly journals Light-Induced Anion Phase Segregation in Mixed Halide Perovskites

2017 ◽  
Vol 3 (1) ◽  
pp. 204-213 ◽  
Author(s):  
Michael C. Brennan ◽  
Sergiu Draguta ◽  
Prashant V. Kamat ◽  
Masaru Kuno
Keyword(s):  
Phase Segregation ◽  
Halide Perovskites

Chemical Heterogeneity in a Single Phase:  Bi0.15Ca0.85MnO3, a Case Example of Macroscopic Phase Segregation

2000 ◽  
Vol 12 (12) ◽  
pp. 3648-3657 ◽  
Author(s):  
A. Llobet ◽  
C. Frontera ◽  
J. L. García-Muñoz ◽  
C. Ritter ◽  
M. A. G. Aranda
Keyword(s):  
Single Phase ◽  
Phase Segregation ◽  
Chemical Heterogeneity

Modeling the Effect of Annealing and Regioregularity on Electron and Hole Transport Characteristics of Bulk Heterojunction Organic Photovoltaic Devices

2010 ◽  
Vol 1270 ◽  
Author(s):  
Shabnam Shambayati ◽  
Bobak Gholamkhass ◽  
Soheil Ebadian ◽  
Steven Holdcroft ◽  
Peyman Servati
Keyword(s):  
Annealing Time ◽  
Electron Mobility ◽  
Bulk Heterojunction ◽  
Acid Methyl Ester ◽  
Hole Mobility ◽  
Phase Segregation ◽  
Hole Transport ◽  
Trap States ◽  
Current Voltage ◽  
Steep Decline

AbstractIn this study, the dark current-voltage characteristics of electron-only and hole-only poly(3-hexyl thiophene) (P3HT):[6,6]-phenyl C61-butyric acid methyl ester (PCBM) as a function of regioregularity (RR) and annealing time is investigated using the mobility edge (ME) model. This model is used to analyze the degradation of electron and hole mobilities as a function of annealing time for 93%-RR and 98%-RR P3HT:PCBM devices. The hole mobility is almost unchanged by the RR nature of P3HT and thermal annealing. The electron mobility, however, behaves differently after annealing. The electron mobility of 98%-RR devices, which is initially higher than that of the 93%-RR devices, experiences a steep decline with annealing. Based on ME analysis, this is due to an increase in trap states in the exponential tail caused by phase segregation of solid state blends of 98%-RR polymer and PCBM. The electron mobility of 93%-RR devices increases with annealing due to an optimization of nano-phase separated morphology.

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