Rational chemical doping of metal halide perovskites

2019 ◽  
Vol 48 (2) ◽  
pp. 517-539 ◽  
Author(s):  
Xinyuan Zhang ◽  
Lina Li ◽  
Zhihua Sun ◽  
Junhua Luo
Keyword(s):  
Metal Halide ◽  
Underlying Structure ◽  
Chemical Doping ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Halide Perovskites

This review summarizes recent significant work on metal-halide doped perovskites, disclosing the underlying structure–property relationships to provide useful insights into their applications.

scholarly journals Mapping Temperature-Dependent Energy-Structure-Property Relationships for Solid Solutions of Inorganic Halide Perovskites

2020 ◽  
Author(s):  
Jack Yang
Keyword(s):  
Solid Solutions ◽  
Band Gaps ◽  
Energy Structure ◽  
Material Research ◽  
Structure Property ◽  
Temperature Dependent ◽  
Orbital Interactions ◽  
Structure Property Relationships ◽  
Data Driven Approach ◽  
Halide Perovskites

Formation of solid solutions with complex compositions has been exhaustively adopted in material research for improving chemical and physical properties. This is also the true for halide perovskites, in the hope of further enhancing their stabilities and reducing the toxicities in lead-containing compounds. Replacement of lead with tin, even partially, is a route to achieve the latter goal. However, this has to be compromised with reduction in band gaps as well as structural stabilities. High-throughput statistical samplings over different configurations for random solid solutions have played pivotal roles in guiding the chemical designs of halide perovskite with better stabilities while retaining high photovoltaic efficiencies, but it remains challenging to intuitively and comprehensively understand the intriguing energy-structure-property (ESP) relationships in solid solutions encompassing multiple degrees-of-freedoms. In this work, first--principle dynamic and electronic structure calculations are performed across 51 different compositions of Cs(Pb$_{x}$Sn$_{1-x}$)X$_{3}$ (X=Cl, Br and I), to systematically reveal the compositional and temperature dependent stabilities, vibrational anharmonicities and band gaps in solid solutions of halide perovskites. This is enabled, in particular, by applying a recently proposed `anharmonicity score' that provides a single numerical metric to characterise the structural dynamics in a multi-atomic system. Further combination with unsupervised machine-learning enable us to produce an ESP map to visually correlate the anharmonicity score with structural distortions and energies. However, temperature-dependent variations in band gap energies, which strongly depend on orbital interactions in metal-halide octrahedra, do not necessarily follow the same trend as anharmonicity scores. This work represents our latest developments in applying data--driven approach to establish ESP relationships for guiding the future designs of functional perovskites.

Role of Spacer Cations and Structural Distortion in Two-Dimensional Germanium Halide Perovskites

2021 ◽  
Author(s):  
Lorenzo Malavasi ◽  
Luca Bindi ◽  
Mauro Coduri ◽  
Filippo De Angelis ◽  
Francesco Fracassi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Metal Halide ◽  
Structural Distortion ◽  
Two Dimensional ◽  
Structure Property ◽  
Structural Distortions ◽  
Metal Halide Perovskite ◽  
Halide Perovskites ◽  
Halide Perovskite

The elucidation of the structure-property correlation in 2D metal halide perovskite is a key issue to understand the dependence of optical properties on structural distortions and to design novel tailored...

scholarly journals Dynamic transformation of cubic copper catalysts during CO2 electroreduction and its impact on catalytic selectivity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Philipp Grosse ◽  
Aram Yoon ◽  
Clara Rettenmaier ◽  
Antonia Herzog ◽  
See Wee Chee ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Copper Catalysts ◽  
Underlying Structure ◽  
Structure Property ◽  
Product Analysis ◽  
Time Resolved ◽  
Catalytic Selectivity ◽  
Structure Property Relationships ◽  
Co2 Electroreduction ◽  
The Impact

AbstractTo rationally design effective and stable catalysts for energy conversion applications, we need to understand how they transform under reaction conditions and reveal their underlying structure-property relationships. This is especially important for catalysts used in the electroreduction of carbon dioxide where product selectivity is sensitive to catalyst structure. Here, we present real-time electrochemical liquid cell transmission electron microscopy studies showing the restructuring of copper(I) oxide cubes during reaction. Fragmentation of the solid cubes, re-deposition of new nanoparticles, catalyst detachment and catalyst aggregation are observed as a function of the applied potential and time. Using cubes with different initial sizes and loading, we further correlate this dynamic morphology with the catalytic selectivity through time-resolved scanning electron microscopy measurements and product analysis. These comparative studies reveal the impact of nanoparticle re-deposition and detachment on the catalyst reactivity, and how the increased surface metal loading created by re-deposited nanoparticles can lead to enhanced C2+ selectivity and stability.

scholarly journals Polymorph engineering of CuMO2 (M = Al, Ga, Sc, Y) semiconductors for solar energy applications: from delafossite to wurtzite

2015 ◽  
Vol 71 (6) ◽  
pp. 702-706 ◽  
Author(s):  
David O. Scanlon ◽  
Aron Walsh
Keyword(s):  
Band Gaps ◽  
Underlying Structure ◽  
Structure Property ◽  
Conducting Oxides ◽  
Energy Applications ◽  
Structure Property Relationships ◽  
Earth Abundant ◽  
Chalcopyrite Lattice ◽  
Group 3 ◽  
The Difference

The cuprous oxide based ternary delafossite semiconductors have been well studied in the context of p-type transparent conducting oxides. CuAlO2, CuGaO2 and CuInO2 represent a homologous series where the electronic properties can be tuned over a large range. The optical transparency of these materials has been associated with dipole forbidden transitions, which are related to the linear O—Cu—O coordination motif. The recent demonstration that these materials can be synthesized in tetrahedral structures (wurtzite analogues of the chalcopyrite lattice) opens up a new vista of applications. We investigate the underlying structure–property relationships (for Group 3 and 13 metals), from the perspective of first-principles materials modelling, towards developing earth-abundant photoactive metal oxides. All materials studied possess indirect fundamental band gaps ranging from 1 to 2 eV, which are smaller than their delafossite counterparts, although in all cases the difference between direct and indirect band gaps is less than 0.03 eV.

scholarly journals Mapping temperature-dependent energy–structure–property relationships for solid solutions of inorganic halide perovskites

2020 ◽  
Vol 8 (47) ◽  
pp. 16815-16825
Author(s):  
Jack Yang
Keyword(s):  
Machine Learning ◽  
Solid Solutions ◽  
Finite Temperature ◽  
Energy Structure ◽  
Structure Property ◽  
Temperature Dependent ◽  
Unsupervised Machine Learning ◽  
Structure Property Relationships ◽  
Electronic Dynamics ◽  
Halide Perovskites

We explored how lead/tin mixing affects the finite-temperature stabilities, atomistic and electronic dynamics of inorganic halide perovskites, with the aid of unsupervised machine learning and the recently devised anharmonicity score.

Structure-property relationships in mechanically stimulated Sorghum bicolor stalks

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Marie-Louise Lemloh ◽  
Anna Pohl ◽  
Eva Weber ◽  
Marco Zeiger ◽  
Petra Bauer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Sorghum Bicolor ◽  
Cross Sections ◽  
Mechanical Stimulation ◽  
Bending Strength ◽  
Experimental System ◽  
Growth Period ◽  
Underlying Structure ◽  
Structure Property ◽  
Structure Property Relationships

AbstractMechanical properties of plants and underlying structure-property relationships are important for agricultural purposes as well as for biomimetic concepts. In this study, the effect of mechanical stimulation on morphology and bending properties of the stalk was investigated for Sorghum bicolor (Poaceae), a widely used drought-tolerant biomass grass. An experimental set-up allowing for defined growth and mechanical perturbation (flexing) during a defined growth period was designed. Mechanical properties of individual internodes of the stalk were determined by three-point bending tests. We found that the three investigated lines showed differences in their general bending strength in the non-stimulated condition. However, similar high range of bending strength values was measured for all plant lines after they underwent the mechanical stimulation procedure. The anatomy of internode cross-sections was examined to evaluate structure-property relationships. An increased thickness of the outer sclerenchymatous tissue was observed for internodes with higher bending strength values. Dried internodes fail under lower strains but showed higher bending strength. These findings show that mechanosensitivity in sorghum is dependent on genetic as well as environmental factors. The experimental system presented here offers new straight-forward possibilities for S. bicolor line selection for applications requiring mechanical strength of the stalk.

Mapping Temperature-Dependent Energy-Structure-Property Relationships for Solid Solutions of Inorganic Halide Perovskites

2020 ◽  
Author(s):  
Jack Yang
Keyword(s):  
Solid Solutions ◽  
Band Gaps ◽  
Energy Structure ◽  
Material Research ◽  
Structure Property ◽  
Temperature Dependent ◽  
Orbital Interactions ◽  
Structure Property Relationships ◽  
Data Driven Approach ◽  
Halide Perovskites

Formation of solid solutions with complex compositions has been exhaustively adopted in material research for improving chemical and physical properties. This is also the true for halide perovskites, in the hope of further enhancing their stabilities and reducing the toxicities in lead-containing compounds. Replacement of lead with tin, even partially, is a route to achieve the latter goal. However, this has to be compromised with reduction in band gaps as well as structural stabilities. High-throughput statistical samplings over different configurations for random solid solutions have played pivotal roles in guiding the chemical designs of halide perovskite with better stabilities while retaining high photovoltaic efficiencies, but it remains challenging to intuitively and comprehensively understand the intriguing energy-structure-property (ESP) relationships in solid solutions encompassing multiple degrees-of-freedoms. In this work, first--principle dynamic and electronic structure calculations are performed across 51 different compositions of Cs(Pb$_{x}$Sn$_{1-x}$)X$_{3}$ (X=Cl, Br and I), to systematically reveal the compositional and temperature dependent stabilities, vibrational anharmonicities and band gaps in solid solutions of halide perovskites. This is enabled, in particular, by applying a recently proposed `anharmonicity score' that provides a single numerical metric to characterise the structural dynamics in a multi-atomic system. Further combination with unsupervised machine-learning enable us to produce an ESP map to visually correlate the anharmonicity score with structural distortions and energies. However, temperature-dependent variations in band gap energies, which strongly depend on orbital interactions in metal-halide octrahedra, do not necessarily follow the same trend as anharmonicity scores. This work represents our latest developments in applying data--driven approach to establish ESP relationships for guiding the future designs of functional perovskites.

Structure-property relationships of PE/PP sandwiched films

1987 ◽  
Vol 45 ◽  
pp. 454-455
Author(s):  
J. Petermann ◽  
G. Broza ◽  
U. Rieck ◽  
A. Jaballah ◽  
A. Kawaguchi
Keyword(s):  
Mechanical Tests ◽  
Polymer Materials ◽  
Ionic Crystals ◽  
Structure Property ◽  
Polymer Systems ◽  
Structure Property Relationships ◽  
Oriented Films ◽  
Materials Used ◽  
Polymer Laminates ◽  
Heated Glass

Oriented overgrowth of polymer materials onto ionic crystals is well known and recently it was demonstrated that this epitaxial crystallisation can also occur in polymer/polymer systems, under certain conditions. The morphologies and the resulting physical properties of such systems will be presented, especially the influence of epitaxial interfaces on the adhesion of polymer laminates and the mechanical properties of epitaxially crystallized sandwiched layers.Materials used were polyethylene, PE, Lupolen 6021 DX (HDPE) and 1810 D (LDPE) from BASF AG; polypropylene, PP, (PPN) provided by Höchst AG and polybutene-1, PB-1, Vestolen BT from Chemische Werke Hüls. Thin oriented films were prepared according to the method of Petermann and Gohil, by winding up two different polymer films from two separately heated glass-plates simultaneously with the help of a motor driven cylinder. One double layer was used for TEM investigations, while about 1000 sandwiched layers were taken for mechanical tests.

Approaches for TEM imaging of cavitation in toughened nylon

1989 ◽  
Vol 47 ◽  
pp. 352-353
Author(s):  
Barbara A. Wood
Keyword(s):  
Morphological Characteristics ◽  
Structure Property ◽  
Polymer Systems ◽  
Selective Staining ◽  
Structure Property Relationships ◽  
Rubber Toughened ◽  
Shear Yield ◽  
Controversial Topic ◽  
Selection Of ◽  
Diamond Knife

A controversial topic in the study of structure-property relationships of toughened polymer systems is the internal cavitation of toughener particles resulting from damage on impact or tensile deformation.Detailed observations of the influence of morphological characteristics such as particle size distribution on deformation mechanisms such as shear yield and cavitation could provide valuable guidance for selection of processing conditions, but TEM observation of damaged zones presents some experimental difficulties.Previously published TEM images of impact fractured toughened nylon show holes but contrast between matrix and toughener is lacking; other systems investigated have clearly shown cavitated impact modifier particles. In rubber toughened nylon, the physical characteristics of cavitated material differ from undamaged material to the extent that sectioning of heavily damaged regions by cryoultramicrotomy with a diamond knife results in sections of greater than optimum thickness (Figure 1). The detailed morphology is obscured despite selective staining of the rubber phase using the ruthenium trichloride route to ruthenium tetroxide.

Catalyst Halogenation Enables Rapid and Efficient Polymerizations with Visible to Near-Infrared Light

2020 ◽  
Author(s):  
Alex Stafford ◽  
Dowon Ahn ◽  
Emily Raulerson ◽  
Kun-You Chung ◽  
Kaihong Sun ◽  
...  
Keyword(s):  
Near Infrared ◽  
Transient Absorption ◽  
Reaction Times ◽  
Infrared Light ◽  
Structure Property ◽  
Light Emitting ◽  
Structure Property Relationships ◽  
Nir Light ◽  
Light Intensities ◽  
Emission Quenching

Driving rapid polymerizations with visible to near-infrared (NIR) light will enable nascent technologies in the emerging fields of bio- and composite-printing. However, current photopolymerization strategies are limited by long reaction times, high light intensities, and/or large catalyst loadings. Improving efficiency remains elusive without a comprehensive, mechanistic evaluation of photocatalysis to better understand how composition relates to polymerization metrics. With this objective in mind, a series of methine- and aza-bridged boron dipyrromethene (BODIPY) derivatives were synthesized and systematically characterized to elucidate key structure-property relationships that facilitate efficient photopolymerization driven by visible to NIR light. For both BODIPY scaffolds, halogenation was shown as a general method to increase polymerization rate, quantitatively characterized using a custom real-time infrared spectroscopy setup. Furthermore, a combination of steady-state emission quenching experiments, electronic structure calculations, and ultrafast transient absorption revealed that efficient intersystem crossing to the lowest excited triplet state upon halogenation was a key mechanistic step to achieving rapid photopolymerization reactions. Unprecedented polymerization rates were achieved with extremely low light intensities (< 1 mW/cm<sup>2</sup>) and catalyst loadings (< 50 μM), exemplified by reaction completion within 60 seconds of irradiation using green, red, and NIR light-emitting diodes.

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