scholarly journals Pressure-Induced Phase Transitions and Bandgap-Tuning Effect of Methylammonium Lead Iodide Perovskite

MRS Advances ◽  
2018 ◽  
Vol 3 (32) ◽  
pp. 1825-1830 ◽  
Author(s):  
Shaojie Jiang ◽  
Yanan Fang ◽  
Ruipeng Li ◽  
Timothy J. White ◽  
Zhongwu Wang ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Ambient Pressure ◽  
Applied Pressure ◽  
Original Structure ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
Methylammonium Lead Iodide ◽  
Peak Pressures ◽  
Bandgap Tuning

ABSTRACTPressure-induced crystallographic transitions and optical behavior of MAPbI3 (MA=methylammonium) were investigated using in-situ synchrotron X-ray diffraction and laser-excited photoluminescence spectroscopy. We observed that the tetragonal phase that presents under ambient pressure transformed to a ReO3-type cubic phase at 0.3 GPa, which further converted into a putative orthorhombic structure at 2.7 GPa. The sample was finally separated into crystalline and amorphous fractions beyond 4.7 GPa. During the decompression, the phase-mixed material restored the original structure in two distinct pathways depending on the peak pressures. Being monitored using a laser-excited photoluminescence technique under each applied pressure, it was determined that the bandgap reduced with an increase of the pressure till 0.3 GPa and then enlarged with an increase of the pressure up to 2.7 GPa. This work lays the foundation for understanding pressure-induced phase transitions and bandgap tuning of MAPbI3, enriching potentially the toolkit for engineering perovskites related photovoltaic devices.

scholarly journals Metastable alloying structures in MAPbI3−xClx crystals

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Wen-Cheng Qiao ◽  
Jianming Yang ◽  
Wei Dong ◽  
Guang Yang ◽  
Qinye Bao ◽  
...  
Keyword(s):  
Optoelectronic Devices ◽  
Close Correlation ◽  
Chloride Ions ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Lead Iodide ◽  
Response Measurement ◽  
H Nmr ◽  
Photoelectric Properties ◽  
Methylammonium Lead Iodide

Abstract Chlorine incorporation engineering has been widely used in optoelectronic devices based on methylammonium lead iodide (MAPbI3) perovskites. However, the characteristics of I/Cl alloying structures in MAPbI3−xClx mixed-halide perovskites and their influences on the optoelectronic properties have been issues of a long-standing controversy. Here, we present a detailed study of the I/Cl alloying structures in MAPbI3−xClx (x = 0.0 to 0.3) single crystals. We found that a small amount of Cl can substitute for the iodide of the PbI3 inorganic lattice, leading to a phase transition from the tetragonal to cubic phase and anomalous cation dynamics evolution. Analyses based on time-dependent X-ray diffraction, 207Pb NMR, and 2H NMR indicate that the alloying structures of the MAPbI3−xClx crystals are metastable and decompose over time. In addition, the photocurrent response measurement of MAPbI3−xClx proved a close correlation between the alloying structures and photoelectric properties of the material. This work sheds light on the essential understanding of the I/Cl alloying structure and provides a plausible explanation for the controversy regarding the role of chloride ions in optoelectronic devices.

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.

Phase transitions in ReO3studied by high-pressure X-ray diffraction

2000 ◽  
Vol 33 (2) ◽  
pp. 279-284 ◽  
Author(s):  
J.-E. Jørgensen ◽  
J. Staun Olsen ◽  
L. Gerward
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Powder Diffraction ◽  
Ambient Pressure ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxygen Ions ◽  
Pressure Phase ◽  
Related Phase

ReO3has been studied at pressures up to 52 GPa by X-ray powder diffraction. The previously observed cubicIm3¯ high-pressure phase was shown to transform to a monoclinic MnF3-related phase at about 3 GPa. All patterns recorded above 12 GPa could be indexed on rhombohedral cells. The compressibility was observed to decrease abruptly at 38 GPa. It is therefore proposed that the oxygen ions are hexagonally close packed above this pressure, giving rise to two rhombohedral phases labelled I and II. The zero-pressure bulk moduliBoof the observed phases were determined and the rhombohedral phase II was found to have an extremely large value of 617 (10) GPa. It was found that ReO3transforms back to thePm3¯mphase found at ambient pressure.

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

Phase Stability and Sintering Behavior of 10mol%Sc2O3–1mol%CeO2–ZrO2 Ceramics

2009 ◽  
Vol 6 (2) ◽  
Author(s):  
Sergey Yarmolenko ◽  
Jag Sankar ◽  
Nicholas Bernier ◽  
Michael Klimov ◽  
Jay Kapat ◽  
...  
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Rhombohedral Phase ◽  
Impurity Level ◽  
Cubic Phase ◽  
Sintering Behavior ◽  
X Ray Diffraction ◽  
Chemical Route ◽  
Heating And Cooling ◽  
Secondary Ion

The phase composition and sintering behavior of two commercially available 10mol%Sc2O3–1mol%CeO2–ZrO2 ceramics produced by Daiichi Kigenso Kagaku Kogyo (DKKK) and Praxair have been studied. DKKK powders have been manufactured using a wet coprecipitation chemical route, and Praxair powders have been produced by spray pyrolysis. The morphology of the powders, as studied by scanning electron microscopy, has been very different. DKKK powders were presented as soft (∼100μm) spherical agglomerates containing 60–100nm crystalline particles, whereas the Praxair powders were presented as sintered platelet agglomerates, up to 30μm long and 3–4μm thick, which consisted of smaller 100–200nm crystalline particles. X-ray diffraction analysis has shown that both DKKK and Praxair powders contained a mixture of cubic (c) and rhombohedral (r) phases: 79% cubic +21% rhombohedral for DKKK powders and 88% cubic +12% rhombohedral for Praxair powders. Higher quantities of the Si impurity level have been detected in Praxair powder as compared to DKKK powder by secondary ion mass spectroscopy. The morphological features, along with differences in composition and the impurity level of both powders, resulted in significantly different sintering behaviors. The DKKK powders showed a more active sintering behavior than of Praxair powders, reaching 93–95% of theoretical density when sintered at 1300°C for 2h. Comparatively, the Praxair powders required high sintering temperatures at 1500–1600°C. However, even at such high sintering temperatures, a significant amount of porosity was observed. Both DKKK and Praxair ceramics sintered at 1300°C or above exist in a cubic phase at room temperature. However, if sintered at 1100°C and 1200°C, the DKKK ceramics exist in a rhombohedral phase at room temperature. The DKKK ceramics sintered at 1300°C or above exhibit cubic to rhombohedral and back to cubic phase transitions upon heating at a 300–500°C temperature range, while Praxair ceramics exist in a pure cubic phase upon heating from room temperature to 900°C. However, if heated rather fast, the cubic to rhombohedral phase transformation could be avoided. Thus it is not expected that the observed phase transitions play a significant role in developing transformation stresses in ScCeZrO2 electrolyte upon heating and cooling down from the operation temperatures.

Effect of Low Pressure on Tetragonal to Cubic Phase Transition of Methylammonium Lead Iodide Perovskite

2020 ◽  
Vol 11 (4) ◽  
pp. 1473-1476 ◽  
Author(s):  
Ansuman Halder ◽  
Yevgeny Rakita ◽  
David Cahen ◽  
Shaibal K. Sarkar
Keyword(s):  
Phase Transition ◽  
Low Pressure ◽  
Cubic Phase ◽  
Lead Iodide ◽  
Methylammonium 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.

Structural and optical properties of methylammonium lead iodide across the tetragonal to cubic phase transition: implications for perovskite solar cells

2016 ◽  
Vol 9 (1) ◽  
pp. 155-163 ◽  
Author(s):  
Claudio Quarti ◽  
Edoardo Mosconi ◽  
James M. Ball ◽  
Valerio D'Innocenzo ◽  
Chen Tao ◽  
...  
Keyword(s):  
Phase Transition ◽  
Optical Properties ◽  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Optical Measurements ◽  
Cubic Phase ◽  
Lead Iodide ◽  
Structural And Optical Properties ◽  
Property Changes ◽  
Methylammonium Lead Iodide

We report optical measurements on MAPbI3solar cells, together withab initiosimulations, to investigate the material property changes across the tetragonal to cubic phase transition.

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