In situ Study of Methylammonium Lead Iodide Inverse Temperature Crystallization

2021 ◽  
Author(s):  
Ryan F. Barrett
Keyword(s):  
Inverse Temperature ◽  
Lead Iodide ◽  
In Situ Study ◽  
Methylammonium Lead Iodide ◽  
Temperature Crystallization

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.

scholarly journals Molecular Dynamics Simulations of Two-Step Process Enable Room-Temperature Synthesis of α-FAPbI3

2020 ◽  
Author(s):  
Paramvir Ahlawat ◽  
Haizhou Lu ◽  
Amita Ummadisingu ◽  
Haiyang Niu ◽  
Michele Invernizzi ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solid Phase ◽  
Perovskite Solar Cells ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
Sequential Deposition ◽  
Solid Phase Transition ◽  
Dynamics Simulations ◽  
Methylammonium Lead Iodide ◽  
Temperature Crystallization

It is well established that the lack of understanding the crystallization process in two-step sequential deposition has a direct impact on efficiency, stability and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occuring during two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, X-ray diffraction and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α-phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that results in the room temperature crystallization of α-formamidinium lead iodide.

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 A combined molecular dynamics and experimental study of two-step process enabling low-temperature formation of phase-pure α-FAPbI3

2021 ◽  
Vol 7 (17) ◽  
pp. eabe3326
Author(s):  
Paramvir Ahlawat ◽  
Alexander Hinderhofer ◽  
Essa A. Alharbi ◽  
Haizhou Lu ◽  
Amita Ummadisingu ◽  
...  
Keyword(s):  
Low Temperature ◽  
Solid Phase ◽  
Perovskite Solar Cells ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
Sequential Deposition ◽  
Phase Pure ◽  
Low Temperature Crystallization ◽  
Methylammonium Lead Iodide ◽  
Temperature Crystallization

It is well established that the lack of understanding the crystallization process in a two-step sequential deposition has a direct impact on efficiency, stability, and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occurring during the two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, x-ray diffraction, and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that result in the low-temperature crystallization of phase-pure α-formamidinium lead iodide.

scholarly journals Molecular Dynamics Simulations of Two-Step Process Enable Room-Temperature Synthesis of α-FAPbI3

2020 ◽  
Author(s):  
Paramvir Ahlawat ◽  
Haizhou Lu ◽  
Amita Ummadisingu ◽  
Haiyang Niu ◽  
Michele Invernizzi ◽  
...  
Keyword(s):  
Room Temperature ◽  
Solid Phase ◽  
Perovskite Solar Cells ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
Sequential Deposition ◽  
Solid Phase Transition ◽  
Dynamics Simulations ◽  
Methylammonium Lead Iodide ◽  
Temperature Crystallization

It is well established that the lack of understanding the crystallization process in two-step sequential deposition has a direct impact on efficiency, stability and reproducibility of perovskite solar cells. Here, we try to understand the solid-solid phase transition occuring during two-step sequential deposition of methylammonium lead iodide and formamidinium lead iodide. Using metadynamics, X-ray diffraction and Raman spectroscopy, we reveal the microscopic details of this process. We find that the formation of perovskite proceeds through intermediate structures and report polymorphs found for methylammonium lead iodide and formamidinium lead iodide. From simulations, we discover a possible crystallization pathway for the highly efficient metastable α-phase of formamidinium lead iodide. Guided by these simulations, we perform experiments that results in the room temperature crystallization of α-formamidinium lead iodide.

Properties of methylammonium lead iodide peerovskite single crystals

2017 ◽  
Vol 58 (8) ◽  
Author(s):  
E. S. Yudanova ◽  
◽  
T. A. Duda ◽  
O. E. Tereshchenko ◽  
O. I. Semenova ◽  
...  
Keyword(s):  
Single Crystals ◽  
Lead Iodide ◽  
Methylammonium Lead Iodide
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