In Situ Observation of Crystallization of Methylammonium Lead Iodide Perovskite from Microdroplets

Small ◽  
2017 ◽  
Vol 13 (26) ◽  
pp. 1604125 ◽  
Author(s):  
Yahui Li ◽  
Zhenhao Zhao ◽  
Feng Lin ◽  
Xiaobing Cao ◽  
Xian Cui ◽  
...  
Keyword(s):  
In Situ Observation ◽  
Lead Iodide ◽  
Methylammonium Lead Iodide

scholarly journals In situ investigation of degradation at organometal halide perovskite surfaces by X-ray photoelectron spectroscopy at realistic water vapour pressure

2017 ◽  
Vol 53 (37) ◽  
pp. 5231-5234 ◽  
Author(s):  
Jack Chun-Ren Ke ◽  
Alex S. Walton ◽  
David J. Lewis ◽  
Aleksander Tedstone ◽  
Paul O'Brien ◽  
...  
Keyword(s):  
Water Vapour ◽  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Water Vapour Pressure ◽  
Lead Iodide ◽  
X Ray ◽  
In Situ Investigation ◽  
Organometal Halide Perovskite ◽  
Methylammonium Lead Iodide

Near-ambient-pressure X-ray photoelectron spectroscopy enables the study of the reaction of in situ-prepared methylammonium lead iodide (MAPI) perovskite at realistic water vapour pressures for the first time.

scholarly journals Out-of-equilibrium processes in crystallization of organic-inorganic perovskites during spin coating

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shambhavi Pratap ◽  
Finn Babbe ◽  
Nicola S. Barchi ◽  
Zhenghao Yuan ◽  
Tina Luong ◽  
...  
Keyword(s):  
Spin Coating ◽  
Grazing Incidence ◽  
Lead Iodide ◽  
In Situ Data ◽  
X Ray Scattering ◽  
Equilibrium Processes ◽  
Complex Phenomena ◽  
Methylammonium Lead Iodide ◽  
Solvent Complex

AbstractComplex phenomena are prevalent during the formation of materials, which affect their processing-structure-function relationships. Thin films of methylammonium lead iodide (CH3NH3PbI3, MAPI) are processed by spin coating, antisolvent drop, and annealing of colloidal precursors. The structure and properties of transient and stable phases formed during the process are reported, and the mechanistic insights of the underlying transitions are revealed by combining in situ data from grazing-incidence wide-angle X-ray scattering and photoluminescence spectroscopy. Here, we report the detailed insights on the embryonic stages of organic-inorganic perovskite formation. The physicochemical evolution during the conversion proceeds in four steps: i) An instant nucleation of polydisperse MAPI nanocrystals on antisolvent drop, ii) the instantaneous partial conversion of metastable nanocrystals into orthorhombic solvent-complex by cluster coalescence, iii) the thermal decomposition (dissolution) of the stable solvent-complex into plumboiodide fragments upon evaporation of solvent from the complex and iv) the formation (recrystallization) of cubic MAPI crystals in thin film.

scholarly journals In-situ ellipsometry measurements on the phase segregation of mixed halide lead perovskites

2021 ◽  
Author(s):  
Annik Bernhardt ◽  
Tharushi Ambagaspitiya ◽  
Martin Kordesch ◽  
Katherine Cimatu ◽  
Jixin Chen
Keyword(s):  
Phase Segregation ◽  
Green Laser ◽  
Bandgap Energy ◽  
Lead Iodide ◽  
Low Light ◽  
Nondestructive Technique ◽  
Methylammonium Lead Iodide ◽  
Conversion Efficiencies ◽  
Reversible Phase

Mixed halide lead perovskite such as methylammonium lead iodide bromides MAPb(BrxI1-x)3 have emerged as one of the most promising materials of future solar cells, offering high power conversion efficiencies and bandgap tunability. Among other factors, the reversible phase segregation under even low light intensities is still limiting their potential use. During this process, the material segregates locally into iodide-rich and bromide-rich phases, lowering the effective bandgap energy. While several studies have been done to illuminate the mechanism and suppression of phase segregation, fundamental aspects remain unclear. Phase compositions after segregation vary extensively between different studies and the exact amounts of phases often remain unmentioned. For iodide-rich phases, the end-point compositions at around x=0.2 are widely accepted but the proportion of the phase is difficult to measure. In this report, we observe the phase segregation using spectroscopic ellipsometry, a powerful, nondestructive technique that has been employed in the study of film degradation before. We obtained dynamic ellipsometric measurements from x=0.5 mixed halide lead perovskite thin films protected by a polystyrene layer under green laser light with a power density of ~11 W/cm2. Changes in the bandgap region can be correlated to the changes in composition caused by phase segregation, allowing for the kinetics to be observed. Time constants between 1.7(± 0.7)×10-3 s-1 for the segregation and 1.5(± 0.6)×10-4 s-1 for recovery were calculated. We expect ellipsometry to serve as a complementary technique to other spectroscopies in studying mixed-halide lead perovskites phase segregation in the future.

In Situ Observation of Catalyzed Gasification of Graphite by Nickel

1981 ◽  
Vol 39 ◽  
pp. 76-77
Author(s):  
R. T. K. Baker ◽  
R. D. Sherwood
Keyword(s):  
Objective Lens ◽  
In Situ Observation ◽  
Gas Flows ◽  
Catalytic Gasification ◽  
Television Camera ◽  
Viewing Screen ◽  
Fuels And Chemicals ◽  
Gasification Of Carbon ◽  
Transmission Microscope

The catalytic gasification of carbon at high temperature by microscopic size metal particles is of fundamental importance to removal of coke deposits and conversion of refractory hydrocarbons into fuels and chemicals. The reaction of metal/carbon/gas systems can be observed by controlled atmosphere electron microscopy (CAEM) in an 100 KV conventional transmission microscope. In the JEOL gas reaction stage model AGl (Fig. 1) the specimen is positioned over a hole, 200μm diameter, in a platinum heater strip, and is interposed between two apertures, 75μm diameter. The control gas flows across the specimen and exits through these apertures into the specimen chamber. The gas is further confined by two apertures, one in the condenser and one in the objective lens pole pieces, and removed by an auxiliary vacuum pump. The reaction zone is <1 mm thick and is maintained at gas pressure up to 400 Torr and temperature up to 1300<C as measured by a Pt-Pt/Rh 13% thermocouple. Reaction events are observed and recorded on videotape by using a Philips phosphor-television camera located below a hole in the center of the viewing screen. The overall resolution is greater than 2.5 nm.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

In situ TEM observations of melting in nanosized eutectic Pb-Cd inclusions embedded in Al

1996 ◽  
Vol 54 ◽  
pp. 986-987
Author(s):  
S. Hagège ◽  
U. Dahmen ◽  
E. Johnson ◽  
A. Johansen ◽  
V.S. Tuboltsev
Keyword(s):  
Electron Microscope ◽  
Melt Spinning ◽  
Ternary Alloys ◽  
Solid Matrix ◽  
Eutectic System ◽  
In Situ Tem ◽  
In Situ Observation ◽  
Orientation Relationships ◽  
Transmission Electron

Small particles of a low-melting phase embedded in a solid matrix with a higher melting point offer the possibility of studying the mechanisms of melting and solidification directly by in-situ observation in a transmission electron microscope. Previous studies of Pb, Cd and other low-melting inclusions embedded in an Al matrix have shown well-defined orientation relationships, strongly faceted shapes, and an unusual size-dependent superheating before melting.[e.g. 1,2].In the present study we have examined the shapes and thermal behavior of eutectic Pb-Cd inclusions in Al. Pb and Cd form a simple eutectic system with each other, but both elements are insoluble in solid Al. Ternary alloys of Al (Pb,Cd) were prepared from high purity elements by melt spinning or by sequential ion implantation of the two alloying additions to achieve a total alloying addition of up to lat%. TEM observations were made using a heating stage in a 200kV electron microscope equipped with a video system for recording dynamic behavior.

In-Situ Observation of Clay Minerals Hydrated and Intercalated With Liquid Chemicals Using Film-Sealed Environmental Cell

1980 ◽  
Vol 38 ◽  
pp. 208-209 ◽  
Author(s):  
K. Fukushima ◽  
N. Kohyama ◽  
A. Fukami
Keyword(s):  
Carbon Film ◽  
Resolving Power ◽  
In Situ Observation ◽  
Interlayer Water ◽  
Saturated Water ◽  
Structure Changes ◽  
Environmental Cell ◽  
Gas Layer ◽  
20 Nm

A film-sealed high resolution environmental cell(E.C) for observing hydrated materials had been developed by us(l). Main specification of the E.C. is as follows: 1) Accelerated voltage; 100 kV. 2) Gas in the E.C.; saturated water vapour with carrier gas of 50 Torr. 3) Thickness of gas layer; 50 μm. 4) Sealing film; evaporated carbon film(20 nm thick) with plastic microgrid. 5) Resolving power; 1 nm. 6) Transmittance of electron beam; 60% at 100 kV. The E.C. had been successfully applied to the study of hydrated halloysite(2) (3). Kaolin minerals have no interlayer water and are basically non-expandable but form intercalation compounds with some specific chemicals such as hydrazine, formamide and etc. Because of these compounds being mostly changed in vacuum, we tried to reveal the structure changes between in wet air and in vacuum of kaolin minerals intercalated with hydrazine and of hydrated state of montmori1lonite using the E.C. developed by us.

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