scholarly journals On the Thermal and Thermodynamic (In)Stability of Methylammonium Lead Halide Perovskites

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Bruno Brunetti ◽  
Carmen Cavallo ◽  
Andrea Ciccioli ◽  
Guido Gigli ◽  
Alessandro Latini
Keyword(s):  
X Ray Diffraction ◽  
Knudsen Effusion ◽  
Term Operation ◽  
Lack Of Information ◽  
Knudsen Effusion Mass Spectrometry ◽  
Halide Perovskites ◽  
The Cost ◽  
Lead Halide ◽  
Very High

Abstract The interest of the scientific community on methylammonium lead halide perovskites (MAPbX3, X = Cl, Br, I) for hybrid organic-inorganic solar cells has grown exponentially since the first report in 2009. This fact is clearly justified by the very high efficiencies attainable (reaching 20% in lab scale devices) at a fraction of the cost of conventional photovoltaics. However, many problems must be solved before a market introduction of these devices can be envisaged. Perhaps the most important to be addressed is the lack of information regarding the thermal and thermodynamic stability of the materials towards decomposition, which are intrinsic properties of them and which can seriously limit or even exclude their use in real devices. In this work we present and discuss the results we obtained using non-ambient X-ray diffraction, Knudsen effusion-mass spectrometry (KEMS) and Knudsen effusion mass loss (KEML) techniques on MAPbCl3, MAPbBr3 and MAPbI3. The measurements demonstrate that all the materials decompose to the corresponding solid lead (II) halide and gaseous methylamine and hydrogen halide and the decomposition is well detectable even at moderate temperatures (~60 °C). Our results suggest that these materials may be problematic for long term operation of solar devices.

scholarly journals Identifying high performance and durable methylammonium-free lead halide perovskites through high throughput synthesis and characterization

2021 ◽  
Author(s):  
Yu An ◽  
Andres Castro ◽  
Ruipeng Li ◽  
Juanita Hidalgo ◽  
Carlo Perini ◽  
...  
Keyword(s):  
Solar Cells ◽  
High Throughput ◽  
High Performance ◽  
Synthesis And Characterization ◽  
Inorganic Hybrid ◽  
Term Operation ◽  
Hybrid Perovskite ◽  
Halide Perovskites ◽  
Lead Halide

One of the organic components in the perovskite photo-absorber, the methylammonium cation, has been suggested to be a roadblock to long-term operation of organic-inorganic hybrid perovskite-based solar cells. In this...

scholarly journals Replacement and Maintenance Decision Analysis for Hydraulic Machinery Facilities at Reservoirs under Imperfect Maintenance

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2507
Author(s):  
Sou-Sen Leu ◽  
Tao-Ming Ying
Keyword(s):  
Cost Effective ◽  
Maintenance Cost ◽  
Imperfect Maintenance ◽  
Term Operation ◽  
Engineering Economics ◽  
Hydraulic Machinery ◽  
Effective Manner ◽  
The Cost ◽  
Replacement Time

After the long-term operation of reservoir facilities, they will become nonoperational due to the material deterioration and the performance degradation. One of crucial decisions is to determine the maintenance or replacement of the facilities in a cost-effective manner. Conventional replacement models seldom consider the maintenance effect. The facilities after maintenance are generally not as good as new, but are relatively restored. The target of this study is to establish a replacement decision model of the reservoir facilities under imperfect maintenance. By combining the theories of reliability analysis, imperfect maintenance, and engineering economics, the best timing of replacement that achieves cost-effectiveness is analyzed and proposed. Lastly, based on the design of experiments (DOE) and simulation, the regression curve chart for the economical replacement decision is established. Once the failure rate, the age of recovery after maintenance, and the ratio of maintenance cost to replacement cost are estimated based on historical data, the cost-effective replacement time of hydraulic machinery facilities will be efficiently determined.

Investigation of Emission Behaviour of Perovskite Nanocrystals into TiO2 Nano to Microsphere

2021 ◽  
Author(s):  
Abha Jha ◽  
Hari Shankar ◽  
Prasenjit Kar
Keyword(s):  
Optoelectronic Devices ◽  
Promising Material ◽  
Perovskite Nanocrystals ◽  
Term Stability ◽  
Long Term Stability ◽  
Halide Perovskites ◽  
Lead Halide

Organic-inorganic methylammonium lead halide perovskites nanocrystals have emerged as a promising material for optoelectronic devices. But due to the lack of long-term stability of perovskite nanocrystals, its applications have been...

scholarly journals Rail Track with Rail Compression

2021 ◽  
Vol 20 (3) ◽  
pp. 234-242
Author(s):  
V. N. Sukhodoev
Keyword(s):  
Effective Property ◽  
Operating Conditions ◽  
Design Parameters ◽  
Labor Costs ◽  
Term Operation ◽  
Rail Track ◽  
Loading And Unloading ◽  
The Stability ◽  
The Cost

The problem of damping the noise on the track, arising from the movement of the train, is solved sufficiently but it is simple, if the rail with spacers is laid inside the longitudinally located band sleeper-mechanism. The result is a layered rail thread, consisting of belts: a rail tape with elastic spacers on three sides, a tie-mechanism tape and a ballast layer. The unity of the layers is carried out due to their own mass. This is the static track without external load. Rail compression is an effective property of rail tracks. It is formed in the sleeper mechanism under the influence of vertical forces with displacements and their horizontal derivatives. When loading the track, the compression is carried out repeatedly with subsequent unloading.n this case, each previous changes in the conditions in work of the track are taken into account in the subsequent cycle of loading and unloading. A rail track with a rail compression is a kind of self-adapting linear system, which is necessary with frequent changes in load and operating conditions for silent performance of a functional purpose. The specificity of this path is that the movement of the wheel creates rail vibration and noise, which are immediately damped by compression with damping. The balance between the occurrence of noise and its suppression is achieved by the ratio of the lengths of half-sleeper shoulders as a lever. The condition for the appearance of a shift of the compression forces in the direction from vertical shoulder of the half-sleepers is the unequal settlements of the horizontal shoulder of the L-shaped half-sleepers and its eccentric loading. As a result of the research, the advantages of a rail track with rail compression have been revealed, which is a guarantor of the stability of the design parameters during long-term operation of the track. The cost of a rail track with rail reduction is halved as a result of steel savings, lower labor costs and operational needs.

scholarly journals Size Isn’t Everything - Compositional Variation in Hybrid Organic-Inorganic Lead Halide Perovskites: Kinetically- versus Thermodynamically-controlled Synthesis

2021 ◽  
Author(s):  
Jiyu Tian ◽  
Eli Zysman-Colman ◽  
Finlay Morrison
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Compositional Variation ◽  
X Ray Diffraction ◽  
Solid Solution Formation ◽  
X Ray ◽  
H Nmr ◽  
Halide Perovskites ◽  
A Site ◽  
Lead Halide

<p>The formation and study of a partial solid solution <a></a><a>Az<sub>1-<i>x</i></sub>FA<i><sub>x</sub></i>PbBr<sub>3</sub></a>, using ‘similar’ sized cations azetidinium (Az<sup>+</sup>) and formamidinium (FA<sup>+</sup>), was explored via mechanosynthesis and precipitation synthesis. The composition and lattice parameters of samples from both syntheses were analysed by <sup>1</sup>H NMR and Rietveld refinement of the powder X-ray diffraction. A clear mismatch in the composition of the perovskite was found between the precipitated samples and the corresponding solutions. Such a mismatch was not observed for samples obtained via mechanosynthesis. The discrepancy suggests products are kinetically-controlled during precipitation, compared to thermodynamically-controlled mechanosynthesis. Furthermore, the cell volume as a function of composition in both 6H (Az-rich) and 3C (FA-rich) solid solutions suggests that FA<sup>+</sup> is actually smaller than Az<sup>+</sup>, contradicting the literature. In the 3C (Az-poor) solid solutions, the extent of Az<sub>1-<i>x</i></sub>FA<i><sub>x</sub></i>PbBr<sub>3 </sub>is unexpectedly smaller than Az<sub>1-<i>x</i></sub>MA<i><sub>x</sub></i>PbBr<sub>3</sub>, again in contradiction to the expectation based on the reported cation sizes. These results indicate that other factors, as yet unidentified, must also contribute to the solid solution formation of organic-inorganic hybrid perovskites, not simply the relative sizes of the A-site cations.</p>

scholarly journals Progressive Polytypism and Bandgap Tuning in Azetidinium Lead Halide Perovskites

2021 ◽  
Author(s):  
Jiyu Tian ◽  
David Cordes ◽  
Alexandra Slawin ◽  
Eli Zysman-Colman ◽  
Finlay Morrison
Keyword(s):  
Linear Variation ◽  
Ambient Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vegard’S Law ◽  
The Family ◽  
Halide Perovskites ◽  
Diffraction Patterns ◽  
Bandgap Tuning ◽  
Lead Halide

<div><div><div><p>Mixed halide azetidinium lead perovskites AzPbBr<sub>3-<i>x</i></sub>X<i><sub>x</sub></i> (X = Cl or I) were obtained by mechanosynthesis. With varying halide composition from Cl- to Br- to I-; the chloride and bromide analogs both form in the hexagonal 6H polytype while the iodide adopts the 9R polytype. An intermediate 4H polytype is observed for mixed Br/I compositions. Overall the structure progresses from 6H to 4H to 9R perovskite polytype with varying halide composition. Rietveld refinement of the powder X-ray diffraction patterns revealed a linear variation in unit cell volume as a function of the average radius of the anion, which is not only observed within the solid solution of each polytype (according to Vegard’s law) but extends uniformly across all three polytypes. This is correlated with a progressive (linear) tuning of the bandgap from 3.41 to 2.00 eV. Regardless of halide, the family of azetidinium halide perovskite polytypes are highly stable, with no discernible change in properties over more than 6 months under ambient conditions</p></div></div></div>

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