scholarly journals A review on advances in doping with alkali metals in halide perovskite materials

2021 ◽  
Vol 3 (12) ◽  
Author(s):  
Madeeha Tabassum ◽  
Qasim Zia ◽  
Yongfeng Zhou ◽  
Michael J. Reece ◽  
Lei Su
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Three Dimensional ◽  
Ion Migration ◽  
Characterization Methods ◽  
Perovskite Materials ◽  
In Doping ◽  
Halide Perovskite ◽  
Induced Changes

AbstractRecent progress in doping of halide perovskite materials (HPM) by using targeted elements has provided a dimension beyond structural and compositional modification, for achieving desired properties and resulting device performance. Herein doping of alkali metal ions (Li+, Na+, K+, Rb+, and Cs+) in three-dimensional HPM is reviewed to lay a particular focus on advances in synthesis, doping-induced changes in optical and electrical properties, and their optoelectronic applications. The introduction of alkali metals in HPM shows an effective route for improved morphology, suppressed ion migration, reduction in non-radiative recombination, passivation of bulk and interface defects, and increased thermal stability. In the end, we provide our perspective that the effect of alkali metal incorporation on the efficiency and stability of HPM should be further investigated via in-situ characterization methods and doped HPM should be considered for more functional applications. Graphical abstract

A Study of the Electrical and Mechanical Properties of Alkali Metal Intercalated Graphite Fibers

1982 ◽  
Vol 20 ◽  
Author(s):  
D.D. Dominguez ◽  
J.L. Lakshmanan ◽  
E.F. Barbano ◽  
J.S. Murday
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Alkali Metal ◽  
Alkali Metals ◽  
Vapor Transport ◽  
Intercalated Graphite ◽  
Graphite Fibers ◽  
Transport Method ◽  
Vapor Transport Method

ABSTRACTIndividual graphite fibers (TP 4104B and GY-70) were intercalated with alkali metals using the two-zone vapor transport method commonly used to prepare alkali metal intercalated graphite. The progress of the reaction was followed in situ by measuring the electrical resistances of the fibers as the temperature difference (ΔT) between the fiber and the metal was decreased stepwise. These measurements showed that the ease and extent of intercalation are related to fiber graphitization. Without exposure to air, the temperature dependence of the resistances of the intercalated fibers were also measured from −196°C to 400°C. The measurements showed that the intercalated fibers have a metallic dependence on temperature. Tensile strength measurements on the intercalated fibers showed that intercalation of the heavy alkali metals is deleterious.

scholarly journals A new on-axis multimode spectrometer for the macromolecular crystallography beamlines of the Swiss Light Source

2009 ◽  
Vol 16 (2) ◽  
pp. 173-182 ◽  
Author(s):  
Robin L. Owen ◽  
Arwen R. Pearson ◽  
Alke Meents ◽  
Pirmin Boehler ◽  
Vincent Thominet ◽  
...  
Keyword(s):  
Light Source ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
X Ray ◽  
X Ray Crystallography ◽  
Additional Information ◽  
Swiss Light Source ◽  
Induced Changes ◽  
Insight Into

X-ray crystallography at third-generation synchrotron sources permits tremendous insight into the three-dimensional structure of macromolecules. Additional information is, however, often required to aid the transition from structure to function. In situ spectroscopic methods such as UV–Vis absorption and (resonance) Raman can provide this, and can also provide a means of detecting X-ray-induced changes. Here, preliminary results are introduced from an on-axis UV–Vis absorption and Raman multimode spectrometer currently being integrated into the beamline environment at X10SA of the Swiss Light Source. The continuing development of the spectrometer is also outlined.

scholarly journals The Role of Different Alkali Metals in the A15Tl27 Type Structure and the Synthesis and X-ray Structure Analysis of a New Substitutional Variant Cs14.53Tl28.4

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7512
Author(s):  
Vanessa F. Schwinghammer ◽  
Susanne M. Tiefenthaler ◽  
Stefanie Gärtner
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Three Dimensional ◽  
Structure Type ◽  
Binary Compound ◽  
Type Structure ◽  
Two Dimensional ◽  
Unique Type ◽  
X Ray ◽  
Quaternary Compounds

Alkali metal thallides have been known since the report of E. Zintl on NaTl in 1932. Subsequently, binary and ternary thallides of alkali metals have been characterized. At an alkali metal proportion of approximately 33% (A:Tl~1:2, A = alkali metal), three different unique type structures are reported: K49Tl108, Rb17Tl41 and A15Tl27 (A = Rb, Cs). Whereas Rb17Tl41 and K49Tl108 feature a three-dimensional sublattice of Tl atoms, the A15Tl27 structure type includes isolated Tl11 clusters as well as two-dimensional Tl-layers. This unique arrangement is only known so far when the heavier alkali metals Rb and Cs are included. In our contribution, we present single-crystal X-ray structure analyses of new ternary and quaternary compounds of the A15Tl27 type structure, which include different amounts of potassium. The crystal structures allow for the discussion of the favored alkali metal for each of the four Wyckoff positions and clearly demonstrate alkali metal dependent site preferences. Thereby, the compound Cs2.27K12.73Tl27 unambiguously proves the possibility of a potassium-rich A15Tl27 phase, even though a small amount of cesium appears to be needed for the stabilization of the latter structure type. Furthermore, we also present two compounds that show an embedding of Tl instead of alkali metal into the two-dimensional substructure, being equivalent to the formal oxidation of the latter. Cs14.53Tl28.4 represents the binary compound with the so far largest proportion of incorporated Tl in the structure type A15Tl27.

scholarly journals Visualizing the role of photoinduced ion migration on photoluminescence in halide perovskite grains

2020 ◽  
Vol 8 (22) ◽  
pp. 7509-7518
Author(s):  
Hoyeon Choi ◽  
Jack Chun-Ren Ke ◽  
Stefan Skalsky ◽  
Christopher A. Castle ◽  
Kexue Li ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Ion Migration ◽  
Carrier Recombination ◽  
Recombination Processes ◽  
Halide Perovskite ◽  
Resolution Mass

By combining in situ optical spectroscopy with a high spatial resolution mass spectrometry, we directly link the evolution in carrier recombination processes in perovskite films to light-induced ion migration.

In-Situ Characterization of Oxide Films on Liquid Alkali Metals Using Second Harmonic Generation (SHG)

1996 ◽  
Vol 451 ◽  
Author(s):  
H. Tostmann ◽  
D. Nattland ◽  
W. Freyland
Keyword(s):  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Alkali Metals ◽  
Surface Characterization ◽  
Second Harmonic ◽  
Pure Metal ◽  
Temperature Dependent ◽  
Characterization Methods

ABSTRACTThe experiments described in this paper clearly show that Second Harmonic Generation (SHG) may be used as a sensitive tool for detecting oxide impurities at interfaces not accessible for usual surface characterization methods. As a striking feature, one peak in the temperature dependent SH intensity is observed for liquid potassium and five peaks for liquid cesium. The occurrence of these peaks cannot be understood in terms of the nonlinear optical properties of the pure metal. By varying the oxygen content present in the melt it can be shown that these peaks must be attributed to the presence of oxide impurities segregating at the interface. In addition it is shown that the presence of oxides at the interface inert sapphire - molten alkali metal significantly alters the structure of the sapphire surface finally leading to corrosion visible even by the eye.

Alkali-Metal Containing Amorphous Carbon: Reactivity and Electronic Structure

1999 ◽  
Vol 593 ◽  
Author(s):  
M. Töwe ◽  
P. Reinke ◽  
P. Oelhafen
Keyword(s):  
Electronic Structure ◽  
Alkali Metal ◽  
Work Function ◽  
Photoelectron Spectroscopy ◽  
Alkali Metals ◽  
Film Surface ◽  
Carbon Films ◽  
Metal Atoms ◽  
Sample Characterization

ABSTRACTAmorphous hydrogen-free carbon films (sp2-dominated a-C) were deposited under ultrahigh vacuum conditions between room temperature and 800°C. These films served as matrices for the in-situ incorporation of alkali-metal atoms (Li, Na). In-situ sample characterization was performed by photoelectron spectroscopy with both x-ray and ultraviolet excitation (XPS, UPS). While the clean metal-containing samples were prepared with metal contents of about 10 at%, a strong oxidation driven accumulation of metal atoms on the film surface exceeding 50 at% was observed upon exposure to molecular oxygen. Work-function measurements by UPS reflected the changes within the electronic structure of the material. Metal incorporation considerably decreased the work-function, but only after oxidation we observed work-functions below the values given for pure alkali metals.

scholarly journals The Low-Dimensional Three-Dimensional Tin Halide Perovskite: Film Characterization and Device Performance

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 2 ◽  
Author(s):  
Cuili Gai ◽  
Jigang Wang ◽  
Yongsheng Wang ◽  
Junming Li
Keyword(s):  
Solar Cells ◽  
High Performance ◽  
3D Structure ◽  
Perovskite Solar Cells ◽  
Three Dimensional ◽  
Physical Parameters ◽  
Perovskite Materials ◽  
Key Points ◽  
Halide Perovskite ◽  
Low Dimensional

Halide perovskite solar cells (PSCs) are considered as one of the most promising candidates for the next generation solar cells as their power conversion efficiency (PCE) has rapidly increased up to 25.2%. However, the most efficient halide perovskite materials all contain toxic lead. Replacing the lead cation with environmentally friendly tin (Sn) is proposed as an important alternative. Today, the inferior performance of Sn-based PSCs mainly due to two challenging issues, namely the facile oxidation of Sn2+ to Sn4+ and the low formation energies of Sn vacancies. Two-dimensional (2D) halide perovskite, in which the large sized organic cations confine the corner sharing BX6 octahedra, exhibits higher formation energy than that of three-dimensional (3D) structure halide perovskite. The approach of mixing a small amount of 2D into 3D Sn-based perovskites was demonstrated as an efficient method to produce high performance perovskite films. In this review, we first provide an overview of key points for making high performance PSCs. Then we give an introduction to the physical parameters of 3D ASnX3 (MA+, FA+, and Cs+) perovskite and a photovoltaic device based on them, followed by an overview of 2D/3D halide perovskites based on ASnX3 (MA+ and FA+) and their optoelectronic applications. The current challenges and a future outlook of Sn-based PSCs are discussed in the end. This review will give readers a better understanding of the 2D/3D Sn-based PSCs.

scholarly journals Gently Does It!: In Situ Preparation of Alkali Metal - Solid Electrolyte Interfaces for Photoelectron Spectroscopy

2021 ◽  
Author(s):  
Joshua Gibson ◽  
Sudarshan Narayanan ◽  
Jack Swallow ◽  
Pardeep Kumar-Thakur ◽  
Mauro Pasta ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Photoelectron Spectroscopy ◽  
Alkali Metals ◽  
Organic Liquid ◽  
Single Layer ◽  
Metal Deposition ◽  
Single Layer Graphene ◽  
Energy Storage Devices ◽  
Electrolyte Interface

The key charge transfer processes in energy storage devices occur at the electrode-electrolyte interface, which is typically buried making it challenging to access the interfacial chemistry. In the case of Li-ion batteries, metallic Li electrodes hold promise for increasing energy and power densities, and when used in conjunction with solid electrolytes (SEs) adverse safety implications associated with dendrite formation in organic liquid electrolytes can potentially be overcome. To better understand the stability of SEs when in contact with alkali metals and the reactions that occur, here we consider the deposition of thin (~10 nm) alkali metal films onto SE surfaces, that are thin enough that X-ray photoelectron spectroscopy can probe the buried electrode-electrolyte interface. We highlight the importance of in situ alkali metal deposition, by assessing the contaminant species that are present after glovebox handling and the use of ‘inert’ transfer devices. Consequently, we compare and contrast three available methods for in situ alkali-metal deposition; Li sputter deposition, Li evaporation, and Li plating induced by e− flood-gun irradiation. Studies on both a sulphide SE (Li6PS5Cl), and a single-layer graphene probe surface reveal that the more energetic Li deposition methods, such as sputtering, can induce surface damage and interfacial mixing that is not seen with thermal evaporation. This indicates that appropriate selection of the Li deposition method for in situ studies is required to observe representative behaviour, and the results of previous studies involving energetic deposition may warrant further evaluation.

Correlated Studies of Cellular Interactions Using TEM, Freeze Etching, and SEM

1974 ◽  
Vol 32 ◽  
pp. 320-321
Author(s):  
J. P. Revel
Keyword(s):  
Developmental Stages ◽  
Three Dimensional ◽  
Cell Movement ◽  
Cellular Interactions ◽  
Serial Sections ◽  
Cell Sheets ◽  
Freeze Etching ◽  
Early Developmental

Movement of individual cells or of cell sheets and complex patterns of folding play a prominent role in the early developmental stages of the embryo. Our understanding of these processes is based on three- dimensional reconstructions laboriously prepared from serial sections, and from autoradiographic and other studies. Many concepts have also evolved from extrapolation of investigations of cell movement carried out in vitro. The scanning electron microscope now allows us to examine some of these events in situ. It is possible to prepare dissections of embryos and even of tissues of adult animals which reveal existing relationships between various structures more readily than used to be possible vithout an SEM.

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