scholarly journals Manipulating efficient light emission in two-dimensional perovskite crystals by pressure-induced anisotropic deformation

2019 ◽  
Vol 5 (7) ◽  
pp. eaav9445 ◽  
Author(s):  
Sheng Liu ◽  
Shishuai Sun ◽  
Chee Kwan Gan ◽  
Andrés Granados del Águila ◽  
Yanan Fang ◽  
...  
Keyword(s):  
Structural Changes ◽  
Light Emission ◽  
Driving Forces ◽  
Quantum Confinement Effect ◽  
Visible Spectrum ◽  
Structural Deformation ◽  
Moderate Pressure ◽  
Two Dimensional ◽  
New Paradigm ◽  
Lead Iodide

The hybrid nature and soft lattice of organolead halide perovskites render their structural changes and optical properties susceptible to external driving forces such as temperature and pressure, remarkably different from conventional semiconductors. Here, we investigate the pressure-induced optical response of a typical two-dimensional perovskite crystal, phenylethylamine lead iodide. At a moderate pressure within 3.5 GPa, its photoluminescence red-shifts continuously, exhibiting an ultrabroad energy tunability range up to 320 meV in the visible spectrum, with quantum yield remaining nearly constant. First-principles calculations suggest that an out-of-plane quasi-uniaxial compression occurs under a hydrostatic pressure, while the energy is absorbed by the reversible and elastic tilting of the benzene rings within the long-chain ligands. This anisotropic structural deformation effectively modulates the quantum confinement effect by 250 meV via barrier height lowering. The broad tunability within a relatively low pressure range will expand optoelectronic applications to a new paradigm with pressure as a tuning knob.

Study on the Effect of Porous Silicon Sizes for Potential Visible Photodetector

2015 ◽  
Vol 815 ◽  
pp. 121-130 ◽  
Author(s):  
Alhan Farhanah Abd Rahim ◽  
N.M. Sah ◽  
I.H. Hamzah ◽  
Siti Noraini Sulaiman ◽  
Musa Mohamed Zahidi
Keyword(s):  
Porous Silicon ◽  
Light Emission ◽  
Spectral Response ◽  
Quantum Confinement Effect ◽  
Visible Spectrum ◽  
Current Gain ◽  
Energy Band Gap ◽  
Current Voltage ◽  
Process Simulator

In this work, the characterization of porous silicon (PS) for potential visible light emission was investigated by simulation. SILVACO TCAD simulator was used to simulate PS by using process simulator, ATHENA and device simulator, ATLAS. Different pore diameter sizes of the PS structures were constructed. The structural, optical and electrical characteristics of the structures PS were investigated by current-voltage (I-V), current gain, spectral response and the energy band gap. It was observed that PS enhances the current gain compare to bulk Si and exhibited photo emission in the visible spectrum which constitutes to the quantum confinement effect of the Si in the PS structures.

Cryo-electron microscopy of two-dimensional crystals of reduced type B botulinum neurotoxin

1992 ◽  
Vol 50 (1) ◽  
pp. 530-531
Author(s):  
P. F. Flicker ◽  
V.S. Kulkarni ◽  
J. P. Robinson ◽  
G. Stubbs ◽  
B. R. DasGupta
Keyword(s):  
Disulfide Bonds ◽  
Clostridium Botulinum ◽  
Structural Changes ◽  
Two Dimensional ◽  
Type B ◽  
Single Chain ◽  
Muscle Paralysis ◽  
Cryo Electron Microscopy ◽  
Disulfide Linkages ◽  
Intracellular Action

Botulinum toxin is a potent neurotoxin produced by Clostridium botulinum. The toxin inhibits release of neurotransmitter, causing muscle paralysis. There are several serotypes, A to G, all of molecular weight about 150,000. The protein exists as a single chain or or as two chains, with two disulfide linkages. In a recent investigation on intracellular action of neurotoxins it was reported that type B neurotoxin can inhibit the release of Ca++-activated [3H] norepinephrine only if the disulfide bonds are reduced. In order to investigate possible structural changes in the toxin upon reduction of the disulfide bonds, we have prepared two-dimensional crystals of reduced type B neurotoxin. These two-dimensional crystals will be compared with those of the native (unreduced) type B toxin.

A Highly Crystalline Anthracene-Based MOF-74 Series Featuring Electrical Conductivity and Luminescence

2019 ◽  
Author(s):  
Patricia Scheurle ◽  
Andre Mähringer ◽  
Andreas Jakowetz ◽  
Pouya Hosseini ◽  
Alexander Richter ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Light Emission ◽  
Block Design ◽  
High Surface ◽  
Visible Spectrum ◽  
Building Blocks ◽  
Divalent Metal Ions ◽  
Conductivity Enhancement ◽  
Surface Areas

Recently, a small group of metal-organic frameworks (MOFs) has been discovered featuring substantial charge transport properties and electrical conductivity, hence promising to broaden the scope of potential MOF applications in fields such as batteries, fuel cells and supercapacitors. In combination with light emission, electroactive MOFs are intriguing candidates for chemical sensing and optoelectronic applications. Here, we incorporated anthracene-based building blocks into the MOF-74 topology with five different divalent metal ions, that is, Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, resulting in a series of highly crystalline MOFs, coined ANMOF-74(M). This series of MOFs features substantial photoluminescence, with ANMOF-74(Zn) emitting across the whole visible spectrum. The materials moreover combine this photoluminescence with high surface areas and electrical conductivity. Compared to the original MOF-74 materials constructed from 2,5-dihydroxy terephthalic acid and the same metal ions Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, we observed a conductivity enhancement of up to six orders of magnitude. Our results point towards the importance of building block design and the careful choice of the embedded MOF topology for obtaining materials with desired properties such as photoluminescence and electrical conductivity.

Driving forces and structural changes of China as a market provider for Korea

2018 ◽  
Vol 22 (3) ◽  
pp. 194-211 ◽  
Author(s):  
Yongqi Feng ◽  
Tianshu Zhang
Keyword(s):  
Steady State ◽  
Driving Force ◽  
Design Methodology ◽  
Structural Changes ◽  
Driving Forces ◽  
Consumption Expenditure ◽  
Input Output ◽  
Content Type ◽  
Fixed Capital Formation ◽  
The Impact

Purpose The purpose of this paper is to provide a better understanding of the driving forces and structural changes of China as a market provider for Korea. This paper gives the answers for the following questions: How do China’s final demands trigger the growth of its imports from Korea? And what’s the impact of China’s final demands on the import in different industries? Design/methodology/approach Based on the Multi-Regional Input-Output model and World Input-Output Table database, this paper constructs the non-competitive imports input-output (IO) table of China to Korea. According to this table, we can calculate the induced imports coefficient and comprehensive induced import coefficients of China’s four final demands for imports from Korea in the 56 industries in China. Findings Among the four driving forces, the strongest one is changes in inventories and valuables. The impact of final consumption expenditure and fixed capital formation is much lower than that of changes in inventories and valuables, but they have a broader impact for the 56 industries. This paper finds out the China’s import induction of the final demands to Korea peaked in 2005 and 2010 and decreased greatly in 2014, so the position of China as market provider for Korea will no longer rise substantially, contrarily it will be in a steady state. Originality/value First, this paper constructs the non-competitive IO table to analyze the market provider issues between two countries and provides practical ways and methods for studies on the issues of imports and market provider. Second, this paper investigates the different roles of four final demands on driving force of China as market provider for Korea and the structural changes of China as a market provider for Korea among 56 industries from 2000 to 2014.

Thiocyanate Containing Two-Dimensional Cesium Lead Iodide Perovskite, Cs2PbI2(SCN)2: Characterization, Photovoltaic Application, and Degradation Mechanism

2018 ◽  
Vol 10 (49) ◽  
pp. 42363-42371 ◽  
Author(s):  
Youhei Numata ◽  
Yoshitaka Sanehira ◽  
Ryo Ishikawa ◽  
Hajime Shirai ◽  
Tsutomu Miyasaka
Keyword(s):  
Degradation Mechanism ◽  
Two Dimensional ◽  
Lead Iodide ◽  
Photovoltaic Application

scholarly journals Two-dimensional photonic crystals increasing vertical light emission from Si nanocrystal-rich thin layers

2018 ◽  
Vol 9 ◽  
pp. 2287-2296
Author(s):  
Lukáš Ondič ◽  
Marian Varga ◽  
Ivan Pelant ◽  
Alexander Kromka ◽  
Karel Hruška ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
Light Emission ◽  
Periodic Structures ◽  
Normal Direction ◽  
Thin Layers ◽  
Two Dimensional ◽  
Lattice Constants ◽  
Leaky Modes ◽  
Si Nanocrystals ◽  
Si Nanocrystal

We have fabricated two-dimensional photonic crystals (PhCs) on the surface of Si nanocrystal-rich SiO2 layers with the goal to maximize the photoluminescence extraction efficiency in the normal direction. The fabricated periodic structures consist of columns ordered into square and hexagonal pattern with lattice constants computed such that the red photoluminescence of Si nanocrystals (SiNCs) could couple to leaky modes of the PhCs and could be efficiently extracted to surrounding air. Samples having different lattice constants and heights of columns were investigated in order to find the configuration with the best performance. Spectral overlap of the leaky modes with the luminescence spectrum of SiNCs was verified experimentally by measuring photonic band diagrams of the leaky modes employing angle-resolved spectroscopy and also theoretically by computing the reflectance spectra. The extraction enhancement within different spatial angles was evaluated by means of micro-photoluminescence spectroscopy. More than 18-fold extraction enhancement was achieved for light propagating in the normal direction and up to 22% increase in overall intensity was obtained at the spatial collection angle of 14°.

Broadband white-light emission with a high color rendering index in a two-dimensional organic–inorganic hybrid perovskite

2018 ◽  
Vol 6 (5) ◽  
pp. 1171-1175 ◽  
Author(s):  
Zhenyue Wu ◽  
Chengmin Ji ◽  
Zhihua Sun ◽  
Sasa Wang ◽  
Sangen Zhao ◽  
...  
Keyword(s):  
White Light ◽  
Light Emission ◽  
White Light Emission ◽  
Two Dimensional ◽  
Inorganic Hybrid ◽  
Hybrid Perovskite ◽  
Color Rendering Index ◽  
Color Rendering

Broadband white-light emission with an ultrahigh CRI of 93 based on an organic–inorganic hybrid 2D corrugated perovskite.

scholarly journals Real-Time Optical and Electronic Sensing with a β-Amino Enone Linked, Triazine-Containing 2D Covalent Organic Framework

2019 ◽  
Author(s):  
Ranjit Kulkarni ◽  
Yu Noda ◽  
Deepak K. Barange ◽  
Yaroslav S. Kochergin ◽  
Barbora Balcarova ◽  
...  
Keyword(s):  
Pore Structure ◽  
Real Time ◽  
Visible Spectrum ◽  
Optical Devices ◽  
Two Dimensional ◽  
Bulk Conductivity ◽  
Electronic Response ◽  
Genuine Use ◽  
Predictive Design ◽  
Electronic Sensing

Fully-aromatic, two-dimensional covalent organic frameworks (2D COFs) are hailed as candidates for electronic and optical devices, yet to-date few applications emerged that make genuine use of their rational, predictive design principles and permanent pore structure. Here, we present a 2D COF made up of chemoresistant β-amino enone bridges and Lewis-basic triazine moieties that exhibits a dramatic real-time response in the visible spectrum and an increase in bulk conductivity by two orders of magnitude to a chemical trigger - corrosive HCl vapours. The optical and electronic response is fully reversible using a chemical switch (NH<sub>3</sub> vapours) or physical triggers (temperature or vacuum). These findings demonstrate a useful application of fully-aromatic 2D COFs as real-time responsive chemosensors and switches.

scholarly journals Real-Time Optical and Electronic Sensing with a β-Amino Enone Linked, Triazine-Containing 2D Covalent Organic Framework

2019 ◽  
Author(s):  
Ranjit Kulkarni ◽  
Yu Noda ◽  
Deepak K. Barange ◽  
Yaroslav S. Kochergin ◽  
Barbora Balcarova ◽  
...  
Keyword(s):  
Pore Structure ◽  
Real Time ◽  
Visible Spectrum ◽  
Optical Devices ◽  
Two Dimensional ◽  
Bulk Conductivity ◽  
Electronic Response ◽  
Genuine Use ◽  
Predictive Design ◽  
Electronic Sensing

Fully-aromatic, two-dimensional covalent organic frameworks (2D COFs) are hailed as candidates for electronic and optical devices, yet to-date few applications emerged that make genuine use of their rational, predictive design principles and permanent pore structure. Here, we present a 2D COF made up of chemoresistant β-amino enone bridges and Lewis-basic triazine moieties that exhibits a dramatic real-time response in the visible spectrum and an increase in bulk conductivity by two orders of magnitude to a chemical trigger - corrosive HCl vapours. The optical and electronic response is fully reversible using a chemical switch (NH<sub>3</sub> vapours) or physical triggers (temperature or vacuum). These findings demonstrate a useful application of fully-aromatic 2D COFs as real-time responsive chemosensors and switches.

scholarly journals Flow patterns of shallow Palic Lake induced by the dominant winds

2012 ◽  
Vol 10 (1) ◽  
pp. 55-67
Author(s):  
Ljubomir Budinski ◽  
Djula Fabian
Keyword(s):  
Numerical Model ◽  
Flow Pattern ◽  
Coriolis Force ◽  
Wind Direction ◽  
Driving Forces ◽  
Open Water ◽  
Flow Patterns ◽  
Two Dimensional ◽  
Lake Model ◽  
Double Gyre

Studies of lake currents have highlighted that in case of stagnant waters winds are the dominant driving forces. This study is dealing with the influence of dominant winds on the flow pattern of Palic Lake. Action of steady winds of different directions has been tested on the lake by means of a two dimensional numerical model, while in addition to winds all other permanent factors like actual bathymetry, inflow and outflow as well the Coriolis force have been accounted for. The experiments have revealed that winds of different directions created corresponding characteristic flow patterns (in base plot), which were similar in cases of winds having opposite directions. However, in such cases the direction of flow was opposite. Moreover, the Palic Lake model produced the well known double-gyre flow pattern: in the coastal strip the direction of the current corresponded to the wind direction, while it was opposite in the domain of open water.

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