Journal articles: 'Perovskites form'

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McDonald, Calum, Chengsheng Ni, Paul Maguire, Paul Connor, John Irvine, Davide Mariotti, and Vladimir Svrcek. "Nanostructured Perovskite Solar Cells." Nanomaterials 9, no. 10 (October 18, 2019): 1481. http://dx.doi.org/10.3390/nano9101481.

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Over the past decade, lead halide perovskites have emerged as one of the leading photovoltaic materials due to their long carrier lifetimes, high absorption coefficients, high tolerance to defects, and facile processing methods. With a bandgap of ~1.6 eV, lead halide perovskite solar cells have achieved power conversion efficiencies in excess of 25%. Despite this, poor material stability along with lead contamination remains a significant barrier to commercialization. Recently, low-dimensional perovskites, where at least one of the structural dimensions is measured on the nanoscale, have demonstrated significantly higher stabilities, and although their power conversion efficiencies are slightly lower, these materials also open up the possibility of quantum-confinement effects such as carrier multiplication. Furthermore, both bulk perovskites and low-dimensional perovskites have been demonstrated to form hybrids with silicon nanocrystals, where numerous device architectures can be exploited to improve efficiency. In this review, we provide an overview of perovskite solar cells, and report the current progress in nanoscale perovskites, such as low-dimensional perovskites, perovskite quantum dots, and perovskite-nanocrystal hybrid solar cells.

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Filip, Marina R., and Feliciano Giustino. "The geometric blueprint of perovskites." Proceedings of the National Academy of Sciences 115, no. 21 (May 7, 2018): 5397–402. http://dx.doi.org/10.1073/pnas.1719179115.

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Perovskite minerals form an essential component of the Earth’s mantle, and synthetic crystals are ubiquitous in electronics, photonics, and energy technology. The extraordinary chemical diversity of these crystals raises the question of how many and which perovskites are yet to be discovered. Here we show that the “no-rattling” principle postulated by Goldschmidt in 1926, describing the geometric conditions under which a perovskite can form, is much more effective than previously thought and allows us to predict perovskites with a fidelity of 80%. By supplementing this principle with inferential statistics and internet data mining we establish that currently known perovskites are only the tip of the iceberg, and we enumerate 90,000 hitherto-unknown compounds awaiting to be studied. Our results suggest that geometric blueprints may enable the systematic screening of millions of compounds and offer untapped opportunities in structure prediction and materials design.

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Wang, Fangfang, Qing Chang, Yikai Yun, Sizhou Liu, You Liu, Jungan Wang, Yinyu Fang, et al. "Hole-Transporting Low-Dimensional Perovskite for Enhancing Photovoltaic Performance." Research 2021 (May 28, 2021): 1–11. http://dx.doi.org/10.34133/2021/9797053.

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Halide perovskites with low-dimensionalities (2D or quasi-2D) have demonstrated outstanding stabilities compared to their 3D counterparts. Nevertheless, poor charge-transporting abilities of organic components in 2D perovskites lead to relatively low power conversion efficiency (PCE) and thus limit their applications in photovoltaics. Here, we report a novel hole-transporting low-dimensional (HT2D) perovskite, which can form a hole-transporting channel on the top surface of 3D perovskite due to self-assembly effects of metal halide frameworks. This HT2D perovskite can significantly reduce interface trap densities and enhance hole-extracting abilities of a heterojunction region between the 3D perovskite and hole-transporting layer. Furthermore, the posttreatment by HT2D can also reduce the crystal defects of perovskite and improve film morphology. As a result, perovskite solar cells (PSCs) can effectively suppress nonradiative recombination, leading to an increasement on photovoltage to >1.20 V and thus achieving >20% power conversion efficiency and >500 h continuous illumination stability. This work provides a pathway to overcome charge-transporting limitations in low-dimensional perovskites and delivers significant enhancements on performance of PSCs.

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Zhang, Taiyang, Yuetian Chen, Miao Kan, Shumao Xu, Yanfeng Miao, Xingtao Wang, Meng Ren, Haoran Chen, Xiaomin Liu, and Yixin Zhao. "MA Cation-Induced Diffusional Growth of Low-Bandgap FA-Cs Perovskites Driven by Natural Gradient Annealing." Research 2021 (August 18, 2021): 1–11. http://dx.doi.org/10.34133/2021/9765106.

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Low-bandgap formamidinium-cesium (FA-Cs) perovskites of FA1-xCsxPbI3 (x<0.1) are promising candidates for efficient and robust perovskite solar cells, but their black-phase crystallization is very sensitive to annealing temperature. Unfortunately, the low heat conductivity of the glass substrate builds up a temperature gradient within from bottom to top and makes the initial annealing temperature of the perovskite film lower than the black-phase crystallization point (~150°C). Herein, we take advantage of such temperature gradient for the diffusional growth of high-quality FA-Cs perovskites by introducing a thermally unstable MA+ cation, which would firstly form α-phase FA-MA-Cs mixed perovskites with low formation energy at the hot bottom of the perovskite films in the early annealing stage. The natural gradient annealing temperature and the thermally unstable MA+ cation then lead to the bottom-to-top diffusional growth of highly orientated α-phase FA-Cs perovskite, which exhibits 10-fold of enhanced crystallinity and reduced trap density (~3.85×1015 cm−3). Eventually, such FA-Cs perovskite films were fabricated into stable solar cell devices with champion efficiency up to 23.11%, among the highest efficiency of MA-free perovskite solar cells.

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Andrei, Florin, Rodica Zăvoianu, and Ioan-Cezar Marcu. "Complex Catalytic Materials Based on the Perovskite-Type Structure for Energy and Environmental Applications." Materials 13, no. 23 (December 5, 2020): 5555. http://dx.doi.org/10.3390/ma13235555.

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This review paper focuses on perovskite-type materials as (photo)catalysts for energy and environmental applications. After a short introduction and the description of the structure of inorganic and hybrid organic-inorganic perovskites, the methods of preparation of inorganic perovskites both as powders via chemical routes and as thin films via laser-based techniques are tackled with, for the first, an analysis of the influence of the preparation method on the specific surface area of the material obtained. Then, the (photo)catalytic applications of the perovskites in energy production either in the form of hydrogen via water photodecomposition or by methane combustion, and in the removal of organic pollutants from waste waters, are reviewed.

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Masharin, Mikhail, Oleksii Peltek, Pavel Talianov, Lev Zelenkov, Mikhail Zuyzin, and Sergey Makarov. "Upconversion photoluminescence of perovskite nanoparticles encapsulated in porous sub-micron spheres supporting Mie resonances." Journal of Physics: Conference Series 2015, no. 1 (November 1, 2021): 012089. http://dx.doi.org/10.1088/1742-6596/2015/1/012089.

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Abstract Currently, halide perovskites are very perspective materials not only for photovoltaics but also for nanophotonic and especially nonlinear optics. These materials have already demonstrated high two-, three- and many- photon absorption coefficients, strong Kerr-nonlinearity, and high-efficient second harmonic generation. Easy and cheap fabrication gives halide perovskites a wide area for scientific research and engineering applications. However, to achieve the stability of perovskites is still a challenging task, which scientific community is working on. In this work, we study a new form of encapsulation of perovskite nanoparticles in sub-micron porous dielectric nanospheres. Due to small pores in such spheres, perovskites are not only protected from external factors, but also are confined in size, which brings several features in the photoluminescence emission. We also show resonant properties of spherical sub-micron particles, which can be used for enhancing upconversion photoluminescence intensity.

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Hou, Yi, Erkan Aydin, Michele De Bastiani, Chuanxiao Xiao, Furkan H. Isikgor, Ding-Jiang Xue, Bin Chen, et al. "Efficient tandem solar cells with solution-processed perovskite on textured crystalline silicon." Science 367, no. 6482 (March 5, 2020): 1135–40. http://dx.doi.org/10.1126/science.aaz3691.

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Stacking solar cells with decreasing band gaps to form tandems presents the possibility of overcoming the single-junction Shockley-Queisser limit in photovoltaics. The rapid development of solution-processed perovskites has brought perovskite single-junction efficiencies >20%. However, this process has yet to enable monolithic integration with industry-relevant textured crystalline silicon solar cells. We report tandems that combine solution-processed micrometer-thick perovskite top cells with fully textured silicon heterojunction bottom cells. To overcome the charge-collection challenges in micrometer-thick perovskites, we enhanced threefold the depletion width at the bases of silicon pyramids. Moreover, by anchoring a self-limiting passivant (1-butanethiol) on the perovskite surfaces, we enhanced the diffusion length and further suppressed phase segregation. These combined enhancements enabled an independently certified power conversion efficiency of 25.7% for perovskite-silicon tandem solar cells. These devices exhibited negligible performance loss after a 400-hour thermal stability test at 85°C and also after 400 hours under maximum power point tracking at 40°C.

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Ben Haj Salah, Maroua, Justine Tessier, Nicolas Mercier, Magali Allain, Antonin Leblanc, Xiaoyang Che, Claudine Katan, and Mikael Kepenekian. "A 3D Lead Iodide Hybrid Based on a 2D Perovskite Subnetwork." Crystals 11, no. 12 (December 16, 2021): 1570. http://dx.doi.org/10.3390/cryst11121570.

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Lead halide perovskites have emerged as promising materials for various optoelectronic applications. For photovoltaics, the reference compound is the 3D perovskite (MA)PbI3 (MA+ = methylammonium). However, this material suffers from instabilities towards humidity or light. This makes the search of new stable 3D lead halide materials very relevant. A strategy is the use of intermediate size cations instead of MA, which are not suitable to form the 3D ABX3 perovskites or 2D perovskites. Here, we report on a novel 3D metal halide hybrid material based on the intermediate size cation hydroxypropylammonium (HPA+), (HPA)6(MA)Pb5I17. We will see that extending the carbon chain length from two CH2 units (in the hydroxylethylammonium cation, HEA+) to three (HPA+) precludes the formation of a perovskite network as found in the lead and iodide deficient perovskite (HEA,MA)1+xPbxI3−x. In (HPA)6(MA)Pb5I17 the 3D lead halide network results from a 2D perovskite subnetworks linked by a PbI6 octahedra sharing its faces. DFT calculations confirm the direct band gap and reveal the peculiar band structure of this 3D network. On one hand the valence band has a 1D nature involving the p orbitals of the halide. On the other, the conduction band possesses a clear 2D character involving hybridization between the p orbitals of the metal and the halide.

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Evans, Christopher D., Simon A. Kondrat, Paul J. Smith, Troy D. Manning, Peter J. Miedziak, Gemma L. Brett, Robert D. Armstrong, et al. "The preparation of large surface area lanthanum based perovskite supports for AuPt nanoparticles: tuning the glycerol oxidation reaction pathway by switching the perovskite B site." Faraday Discussions 188 (2016): 427–50. http://dx.doi.org/10.1039/c5fd00187k.

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Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area. We report the use of a supercritical carbon dioxide anti-solvent precipitation methodology to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible. These catalysts were used for the selective oxidation of glycerol. By changing the elemental composition of the perovskite B site, we dramatically altered the reaction pathway between a sequential oxidation route to glyceric or tartronic acid and a dehydration reaction pathway to lactic acid. Selectivity profiles were correlated to reported oxygen adsorption capacities of the perovskite supports and also to changes in the AuPt nanoparticle morphologies. Extended time on line analysis using the best oxidation catalyst (AuPt/LaMnO₃) produced an exceptionally high tartronic acid yield. LaMnO₃ produced from alternative preparation methods was found to have lower activities, but gave comparable selectivity profiles to that produced using the supercritical carbon dioxide anti-solvent precipitation methodology.

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Long, Youwen. "High-pressure synthesis and physical properties of A-site ordered perovskites." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C755. http://dx.doi.org/10.1107/s2053273314092444.

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ABO3-type perovskite oxides exhibit a wide variety of interesting physical properties such as superconductivity, colossal magnetoresistance, multiferroic behavior etc. For a simple ABO3 perovskite, if three quarters of the A site is replaced by a transition metal A', then the so-called A-site ordered double perovskite with the chemical formula of AA'3B4O12 can form. Since both A' and B sites accommodate transition metal ions, in addition to conventional B-B interaction, the new A'-A' and/or A'-B interaction is possible to show up, giving rise to the presence of many novel physical properties. Here we will show our recent research work on the high-pressure synthesis of several A-site ordered perovskites as well as a series of interesting physical properties like temperature- and pressure-induced intermetallic charge transfer, negative thermal expansion, magnetoelectric coupling multiferroic and so on. [1-3]

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Zhao, Tingting, Haoran Yu, Xuyingnan Tao, Feiyang Yu, Ming Li, and Haiqian Wang. "Influences of Ni Content on the Microstructural and Catalytic Properties of Perovskite LaNixCr1−xO3 for Dry Reforming of Methane." Catalysts 12, no. 10 (September 29, 2022): 1143. http://dx.doi.org/10.3390/catal12101143.

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Perovskite oxides were widely used as precursors for developing metal-support type catalysts. It is attractive to explore the catalytic properties of the oxides themselves for dry reforming of methane (DRM). We synthesized LaNixCr1−xO3 (x = 0.05–0.5) samples in powder form using the sol-gel self-combustion method. Ni atoms are successfully doped into the LaCrO3 perovskite lattice. The perovskite grains are polycrystalline, and the crystallite size decreases with increasing Ni content. We demonstrated that the LaNixCr1−xO3 perovskites show intrinsically catalytic activity for DRM reactions. Reducing the Ni content is helpful to reduce carbon deposition resulting from the metal Ni nanoparticles that usually coexist with the highly active perovskite oxides. The CH4 conversion over the LaNi0.1Cr0.9O3 sample reaches approximately 84% at 750 °C, and the carbon deposition is negligible.

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Vu The, Ninh, Dung Nguyen Viet, Dai Luu Minh, and Anh Nguyen Thanh. "Application of adsorbents based on LaFe1-xMnxO3 perovskites to treat As, Pb in contaminated groundwater in the craft village." Vietnam Journal of Catalysis and Adsorption 10, no. 1S (October 15, 2021): 218–23. http://dx.doi.org/10.51316/jca.2021.126.

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The nanoparticle crystals of perovskite LaFe1-xMnxO3 were prepared by the PVA (polyvinyl alcohol) gel combustion method to determine the adsorption capacity of As(V), Pb2+ from solution was investigated. Single-phase crystalline perovskite of LaFe1-xMnxO3 is formed by solid solution formation which completely replaces LaFeO3 perovskite and LaMnO3 perovskite. In LaFe1-xMnxO3 perovskites, the x substitution composition, or the rate of participation to form the substitution solid solution between the two components LaFeO3 and LaMnO3 will determine the type of original structure, the interaction between the Fe and Mn in in the crystal lattice. Thereby determining the characteristics and adsorption activity of perovskite LaFe1-xMnxO3. Perovskite LaFe1-xMnxO3 with the formula LaFe0.3Mn0.7O3 gave the best As(V) adsorption efficiency on the x components, while the LaFe0.7Mn0.3O3 formula gave the best As(V) adsorption efficiency on the x components. The LaFe1-xMnxO3 perovskite-based adsorbent pelletized with the composition LaFe0.3Mn0.7O3-LaFe0.7Mn0.3O3-bentonite has practical potential to remove arsenic, lead in contaminated water.

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Zhu, Xixiang, Liping Peng, Jinpeng Li, Haomiao Yu, and Yulin Xie. "Formation of a Fast Charge Transfer Channel in Quasi-2D Perovskite Solar Cells through External Electric Field Modulation." Energies 14, no. 21 (November 5, 2021): 7402. http://dx.doi.org/10.3390/en14217402.

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Quasi-2D perovskites solar cells exhibit excellent environmental stability, but relatively low photovoltaic properties, compared with 3D perovskites solar cells. However, charge transport and extraction in quasi-2D perovskite solar cells are still limited by the inevitable quantum well effect, resulting in low power conversion efficiency (PCE). To date, most efforts concentrate on crystal orientation and favorable alignment during materials and films processing. In this paper, we demonstrated that the quasi-2D perovskite [(BA)2(MA)3Pb4I13 (n = 4)] solar cells show an optimized device performance through forming a fast charge transfer channel among 2D quantum wells through external electric field modulation, with appropriate modulation bias and time after the device has been fabricated. Essentially, ions will move directionally due to local polarization in quasi-2D perovskite solar cells under the action of electric field modulation. More importantly, the mobile ions function as a dopant to de-passivate the defects when releasing at grain boundaries, while decreasing built-in potential by applying forward modulation bias with proper modulation time. The capacitance-voltage characteristics indicate that electric field modulation can decrease the charge accumulation and improve the charge collection in quasi-2D perovskite solar cells. Photoluminescence (PL) studies confirm that the non-radiative recombination is reduced by electric field modulation, leading to enhanced charge transfer. Our work indicates that external electric field modulation is an effective method to form a fast charge transfer channel among 2D quantum wells, leading to enhanced charge transfer and charge collection through local polarization toward developing high–performance quasi-2D perovskite devices.

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Cordero, Francesco, Floriana Craciun, Anna Maria Paoletti, and Gloria Zanotti. "Structural Transitions and Stability of FAPbI3 and MAPbI3: The Role of Interstitial Water." Nanomaterials 11, no. 6 (June 18, 2021): 1610. http://dx.doi.org/10.3390/nano11061610.

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We studied the influence of water on the structural stability and transformations of MAPI and FAPI by anelastic and dielectric spectroscopies under various temperature and H2O partial pressure protocols. Before discussing the new results in terms of interstitial water in MAPI and FAPI, the literature is briefly reviewed, in search of other studies and evidences on interstitial water in hybrid halide perovskites. In hydrated MAPI, the elastic anomaly between the cubic α and tetragonal β phases may be depressed by more than 50%, demonstrating that there are H2O molecules dispersed in the perovskite lattice in interstitial form, that hinder the long range tilting of the PbI6 octahedra. Instead, in FAPI, interstitial water accelerates in both senses the reconstructive transformations between 3D α and 1D δ phases, which is useful during the crystallization of the α phase. On the other hand, the interstitial H2O molecules increase the effective size of the MA and FA cations to which are bonded, shifting the thermodynamic equilibrium from the compact perovskite structure to the open δ and hydrated phases of loosely bonded chains of PbI6 octahedra. For this reason, when fabricating devices based on hybrid metal-organic halide perovskites, it is important to reduce the content of interstitial water as much as possible before encapsulation.

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Kostopoulou, Athanasia, and Dimitra Vernardou. "Special Issue: Perovskite Nanostructures: From Material Design to Applications." Nanomaterials 12, no. 1 (December 29, 2021): 97. http://dx.doi.org/10.3390/nano12010097.

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In the past decade, perovskite materials have attracted great scientific and technological interest due to their interesting opto-electronic properties. Nanostructuring of the perovskites, due to their reduced dimensions are advantageous in offering large surface area, controlled transport and charge carrier mobility, strong absorption and photoluminescence, and confinement effects. These features, together with the unique tunability in composition, shape, and functionalities in addition to the ability to form efficient, low-cost, and light-active structures make the perovskite nanostructures efficient functional components for multiple applications, ranging from photovoltaics and batteries to lasing and light-emitting diodes. The purpose of this Special Issue is to give an overview of the latest experimental findings concerning the tunability in composition, shape, functionalities, growth conditions, and synthesis procedures of perovskite structures and to identify the critical parameters for producing materials with functional characteristics.

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Pujiarti, Herlin, Rahmat Hidayat, and Priastuti Wulandari. "Effect of Lead-Free Perovskite Cs₂SnI₆ Addition in the Structure of Dye-Sensitized Solar Cell." Key Engineering Materials 860 (August 2020): 22–27. http://dx.doi.org/10.4028/www.scientific.net/kem.860.22.

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Over the past few years, metal halide perovskites have been considered as a promising material for application in photovoltaic devices because of its unique optical and electrical properties. In particular, Sn-based perovskites have been being considered to replace Pb-based perovskite because of the Pb toxicity that will raise serious concerns on the environmental issue. In this report, we present our attempt to synthesize the Sn-based perovskite (namely, Cs2SnI6), which is air and thermal stable, and use it as an electron transport layer in dye-sensitized solar cells (DSSC) for improving its power conversion efficiency. The synthesize of Cs2SnI6 perovskite was done by mixing Cs2CO3 in HI and SnI4 in ethanol to form a precipitate at room temperature. The purification process was an important part to collect effectively the synthesis product. The fabrication of DSSC was done by a standard process based on the screen printing and spin-coating techniques, while the characterization of Cs2SnI6 was done by UV-Vis spectroscopy and XRD measurement. In the present experiment, the addition of the Cs2SnI6 layer was performed by spin coating the Cs2SnI6 solution onto the TiO2 mesoporous layer. The photovoltaic performance of the fabricated DSSC shows a significant enhancement in the short circuit photocurrent density (Jsc) and conversion efficiency, that is, from 15.04 mA/cm2 to 16.33 mA/cm2 from 5.7% to 6.75% due to the incorporation of spin-coated 5 mM Cs2SnI6 in comparison to the reference cell without Cs2SnI6.

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Khalfin, Sasha, and Yehonadav Bekenstein. "Advances in lead-free double perovskite nanocrystals, engineering band-gaps and enhancing stability through composition tunability." Nanoscale 11, no. 18 (2019): 8665–79. http://dx.doi.org/10.1039/c9nr01031a.

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In this topical review, we have focused on the recent advances made in the studies of lead-free perovskites in the bulk form and as nanocrystals. We highlight how nanocrystals can serve as model systems to explore the schemes of cationic exchange, doping and alloying for engineering the electronic structure of double perovskites.

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Tochyniuk, Pavlo, Oleg Vyunov, Aleksandr Ishchenko, Irina Kurdyukova, Viktor Vlasyuk, Vitaliy Kostylyov, and Anatolii Belous. "ORGANIC-INORGANIC PEROVSKITE CH3NH3PbI3: MORPHOLOGICAL, STRUCTURAL AND PHOTOELECTROPHYSICAL PROPERTIES." Ukrainian Chemistry Journal 85, no. 9 (October 16, 2019): 31–41. http://dx.doi.org/10.33609/0041-6045.85.9.2019.31-41.

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The organic-inorganic perovskite films CH3N-H3PbI3 were synthesized from solutions with different ratios of initial reagents (PbI2 to CH3NH3I were taken in the ratio 1:1, 1:2 and 1:3). To deposit films of organic-inorganic perovskite, solutions with different ratio of initial reagents were applied to the substrates by the spin-coating method. The organic-inorganic perovskites synthesized were of one chemical composition in spite of the fact that different chemical reactions proceeded during the synthesis. It was found that the formation of perovskite occurs according to different schemes depending on the ra-tio of PbI2 and CH3NH3I: without the formation of intermediate compounds (at ratio 1:1) and with the formation of one (CH3NH3)2PbI4 (1:2) and two intermediate compounds (CH3NH3)3PbI5, (CH3NH3)2PbI4 (1:3).It was established that regardless of the ratio of the initial reagents, organic-inorganic perovskites with different morphology are formed. At the ratio of the initial reagents 1:1, needle particles formed, and at the ratio of 1:2 and 1:3, particles have the form of a maple leaf and round shape, respectively.To improve the film stability, polyvinyl butyral polymer was used. It is an amorphous colorless pol-ymer which is characterized by high optical properties, environmental (in particular, H2O, O2 and O3) and light resistance. The stability of films of organic-inorganic perovskite without and with a polymer were investigated by XRD, fluorescence spectroscopy and non-contact optical methods. The stability of the films was evaluated by the content of the additional phase of PbI2, which is formed due to the degradation of the organic-inorganic perovskite film CH3NH3PbI3. It was established that the presence of a polymer layer results in improved stability of samples and decrease the rate of surface recombination velocity compared to samples without a polymer layer.The diffusion length of minority charge carriers of the organic-inorganic perovskite films with the polymeric layer was estimated by the method of spectral dependences of the surface photovoltage. The spectra of surface photovoltage and the diffusion length of minority charge carriers of organic-inorganic perovskites with a polymer layer were compared with the literature data for samples without a polymer layer. This comparison shown that the characteristics of the samples with polymer layer are somewhat worse. It is determined that the organic-inorganic perovskite with the polymer layer is characterized by a smaller diffusion length (by 10%) of the minority charge carriers. The prepared perovskite films CH3NH3PbI3 are promising for the development of effective solar cells.

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Iyasele, E. O. "A COMPREHENSIVE REVIEW OF PHOTOVOLTAIC DEVICES BASED ON PEROVSKITES." Open Journal of Engineering Science (ISSN: 2734-2115) 1, no. 1 (March 10, 2020): 26–52. http://dx.doi.org/10.52417/ojes.v1i1.82.

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Perovskite solar cells (PSCs) though in its development stage, has been of interest to Scientists receiving considerable attention in recent years as a promising material capable of developing high performance photovoltaic devices at low cost. Owing to their solution processability, broad spectrum solar absorption, low non-radiative recombination losses, etc., PSCs provide numerous advantages over most thin ﬁlm absorber materials. Due to the substantial improvement of Power Conversion Efficiency (PCE) of these materials, photovoltaic efficiency has reached prestigious position (approx. 20.1 %) within the last 5 years. In this review article, we discuss the current state of the Art for photovoltaic devices based on Perovskites, highlighting the underlying phenomenon, synthesis, challenges, comparison to other technologies and future outlook. We emphasized the importance of Perovskite ﬁlm formation and qualities in achieving highly efficient photovoltaic devices. The flexibility and simplicity of Perovskite fabrication methods allows the use of mesoporous and planar device architectures. A variety of processing techniques are currently employed to form the highest quality CH3NH3PbX3 ﬁlms resulting to high performance PSC devices which include stoichiometry, thermal annealing, solvent engineering, additives and environmental control. In this review, we outlined and discussed the challenges of PSCs including its stability issues, hysteresis effects, and ion migration effects. Possible ways overcoming these challenges and improvement on the stability of PSCs so far were also addressed. Iyasele, E. O. | Mechanical Engineering Department, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria

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Sattar, Abdul, Nadia Shahzad, Muhammad Ali Tariq, Tanzeela Yousaf, Muhammad Salik Qureshi, Muhammad Imran Shahzad, Rabia Liaquat, and Majid Ali. "Carbonyl functional group assisted crystallization of mixed tin–lead narrow bandgap perovskite absorber in ambient conditions." Applied Physics Letters 121, no. 7 (August 15, 2022): 073901. http://dx.doi.org/10.1063/5.0099988.

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Tin–lead (Sn–Pb) perovskite solar cells are receiving growing interest due to their applications in tandems and lead mitigation. Nonetheless, fast crystallization and facile Sn2+ oxidation restrict their ambient fabrication, which increases fabrication costs. This Letter presents an experimental study on additive assisted growth of FA0.2MA0.8Sn0.5Pb0.5I2.4Br0.6 narrow bandgap perovskite films employing a Lewis-base molecule, caffeine (1,3,7-trimethylpurine-2,6-dione), having two carbonyl functional groups (C = O) in ambient conditions (relative humidity < ∼10%). The C = O interacts with metallic ions (Sn2+ and Pb2+) via chelation to form an acid–base adduct, slowing down the fast crystallization of FA0.2MA0.8Sn0.5Pb0.5I2.4Br0.6 perovskite films. As a result, the grain size improves resulting in better structural and optical properties. In contrast, Urbach energy values showed higher electronic disorder near the band edges even upon caffeine doping implying Sn4+ doping in an ambient environment. This work accentuates the potential of the acid–base adduction to regulate uncontrolled crystallization of Sn–Pb perovskites in the ambient environment.

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Nikovskiy, Igor A., Kseniya L. Isakovskaya, and Yulia V. Nelyubina. "New Low-Dimensional Hybrid Perovskitoids Based on Lead Bromide with Organic Cations from Charge-Transfer Complexes." Crystals 11, no. 11 (November 21, 2021): 1424. http://dx.doi.org/10.3390/cryst11111424.

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We have obtained a series of low-dimensional hybrid perovskitoids (often referred to as perovskites) based on lead bromide. As organic cations, the derivatives of polyaromatic and conjugated molecules, such as anthracene, pyrene and (E)-stilbene, were chosen to form charge-transfer complexes with various organic acceptors for use as highly tunable components of hybrid perovskite solar cells. X-ray diffraction analysis showed these crystalline materials to be new 1D- and pseudo-layered 0D-perovskitoids with lead bromide octahedra featuring different sharing modes, such as in unusual mini-rods of four face- and edge-shared octahedra. Thanks to the low dimensionality, they can be of use in another type of optoelectronic device, photodetectors.

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Poudel, Ujjwal, Madhu Sudhan Bhusal, Manish Bhurtel, Atish Adhikari, and Narayan Prasad Adhikari. "Machine Learning in Predicting Lattice Constant of Cubic Perovskite Oxides." Journal of Nepal Physical Society 8, no. 1 (December 13, 2022): 27–34. http://dx.doi.org/10.3126/jnphyssoc.v8i1.48282.

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A sample of 3,115 data of perovskite oxides in the form of ABO3 (A and B being the cations) was taken for this study of the application of machine learning in predicting the lattice constants (a determining factor in material design). The ANN, DT, RF, KNN, and SVM models were used to predict the lattice constants of perovskites because machine learning techniques have been phenomenal in uncovering crystal structures in the field of material research in recent years. These models used properties like ionic radii, formation energy, and band gap as input features. The R2 score was used to assess the regression model’s performance. The Random Forest Regression Model outperforms all other regression models regarding dataset and features.

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Lo Faro, Massimiliano, Sabrina Campagna Zignani, and Antonino Salvatore Aricò. "Lanthanum Ferrites-Based Exsolved Perovskites as Fuel-Flexible Anode for Solid Oxide Fuel Cells." Materials 13, no. 14 (July 20, 2020): 3231. http://dx.doi.org/10.3390/ma13143231.

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Exsolved perovskites can be obtained from lanthanum ferrites, such as La0.6Sr0.4Fe0.8Co0.2O3, as result of Ni doping and thermal treatments. Ni can be simply added to the perovskite by an incipient wetness method. Thermal treatments that favor the exsolution process include calcination in air (e.g., 500 °C) and subsequent reduction in diluted H2 at 800 °C. These processes allow producing a two-phase material consisting of a Ruddlesden–Popper-type structure and a solid oxide solution e.g., α-Fe100-y-zCoyNizOx oxide. The formed electrocatalyst shows sufficient electronic conductivity under reducing environment at the Solid Oxide Fuel Cell (SOFC) anode. Outstanding catalytic properties are observed for the direct oxidation of dry fuels in SOFCs, including H2, methane, syngas, methanol, glycerol, and propane. This anode electrocatalyst can be combined with a full density electrolyte based on Gadolinia-doped ceria or with La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) or BaCe0.9Y0.1O3-δ (BYCO) to form a complete perovskite structure-based cell. Moreover, the exsolved perovskite can be used as a coating layer or catalytic pre-layer of a conventional Ni-YSZ anode. Beside the excellent catalytic activity, this material also shows proper durability and tolerance to sulfur poisoning. Research challenges and future directions are discussed. A new approach combining an exsolved perovskite and an NiCu alloy to further enhance the fuel flexibility of the composite catalyst is also considered. In this review, the preparation methods, physicochemical characteristics, and surface properties of exsoluted fine nanoparticles encapsulated on the metal-depleted perovskite, electrochemical properties for the direct oxidation of dry fuels, and related electrooxidation mechanisms are examined and discussed.

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Kumar, Abhishek, Ankur Solanki, Manukumara Manjappa, Sankaran Ramesh, Yogesh Kumar Srivastava, Piyush Agarwal, Tze Chien Sum, and Ranjan Singh. "Excitons in 2D perovskites for ultrafast terahertz photonic devices." Science Advances 6, no. 8 (February 2020): eaax8821. http://dx.doi.org/10.1126/sciadv.aax8821.

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In recent years, two-dimensional (2D) Ruddlesden-Popper perovskites have emerged as promising candidates for environmentally stable solar cells, highly efficient light-emitting diodes, and resistive memory devices. The remarkable existence of self-assembled quantum well (QW) structures in solution-processed 2D perovskites offers a diverse range of optoelectronic properties, which remain largely unexplored. Here, we experimentally observe ultrafast relaxation of free carriers in 20 ps due to the quantum confinement of free carriers in a self-assembled QW structures that form excitons. Furthermore, hybridizing the 2D perovskites with metamaterials on a rigid and a flexible substrate enables modulation of terahertz fields at 50-GHz modulating speed, which is the fastest for a solution-processed semiconductor-based photonic device. Hence, an exciton-based ultrafast response of 2D perovskites opens up large avenues for a wide range of scalable dynamic photonic devices with potential applications in flexible photonics, ultrafast wavefront control, and short-range wireless terahertz communications.

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25

Rodrigues, Ana Sofia, Lurdes Ciríaco, Maria José Pacheco, Annabel Fernandes, Sandra Mogo, and Ana Lopes. "Sunlight-Driven AO7 Degradation with Perovskites (La,Ba)(Fe,Ti)O3 as Heterogeneous Photocatalysts." Nanomaterials 11, no. 11 (November 21, 2021): 3142. http://dx.doi.org/10.3390/nano11113142.

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Perovskites of the (La,Ba)(Fe,Ti)O3 family were prepared, characterized, and utilized as heterogeneous photocatalysts, activated by natural sunlight, for environmental remediation of Acid Orange 7 (AO7) aqueous solutions. Catalysts were prepared by the ceramic (CM) and the complex polymerization (CP) methods and characterized by XRD, SEM, EDS, and band gap energy. It was found that catalytic properties depend on the synthesis method and annealing conditions. In the photocatalytic assays with sunlight, different AO7 initial concentrations and perovskite amounts were tested. During photocatalytic assays, AO7 and degradation products concentrations were followed by HPLC. Only photocatalysis with BaFeO3-CM and BaTiO3-CP presented AO7 removals higher than that observed for photolysis. However, photolysis leads to the formation of almost exclusively amino-naphthol and sulfanilic acid, whereas some of the perovskites utilized form less-toxic compounds as degradation products, such as carboxylic acids (CA). Partial substitution of Ba by La in BaTiO3-CM does not produce any change in the photocatalytic properties, but the replacement of Ti by Fe in the La0.1Ba0.9TiO3 leads to reduced AO7 removal rate, but with the formation of CAs. The best AO7 removal (92%) was obtained with BaFeO3-CM (750 mg L−1), after 4 h of photocatalytic degradation with solar radiation.

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Khorramshahi, Fatemeh, and Arash Takshi. "Microfluidic Approach for Lead Halide Perovskite Flexible Phototransistors." Electronics 9, no. 11 (November 5, 2020): 1852. http://dx.doi.org/10.3390/electronics9111852.

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Lead halide perovskites possess outstanding optical characteristics that can be employed in the fabrication of phototransistors. However, due to low current modulation at room temperature, sensitivity to the ambient environment, lack of patterning techniques and low carrier mobility of polycrystalline form, investigation in perovskite phototransistors has been limited to rigid substrates such as silicon and glass to improve the film quality. Here, we report on room temperature current modulation in a methylammonium lead iodide perovskite (MAPbI3) flexible transistor made by an extremely cheap and facile fabrication process. The proposed phototransistor has the top-gate configuration with a lateral drain–channel–source structure. The device performed in the linear and saturation regions both in the dark and under white light in different current ranges according to the illumination conditions. The transistor showed p-type transport characteristics and the field effect mobility of the device was calculated to be ~1.7 cm2 V−1 s−1. This study is expected to contribute to the development of MAPbI3 flexible phototransistors.

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Tian, W., J. C. Jiang, X. Q. Pan, J. H. Haeni, and D. G. Schlom. "Atomic Structure Of Epitaxial Thin Films Of The Srn+1tinO3n+1 Ruddlesden-Popper Homologous Series." Microscopy and Microanalysis 5, S2 (August 1999): 114–15. http://dx.doi.org/10.1017/s1431927600013891.

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The n+1TinO3n+1 Ruddlesden-Popper homologous series are promising candidates in the search for low loss tunable dielectric materials. SrTiO3 (n=∞) has the perovskite structure with alternating TiO2 and SrO layers. However, those members of the n+1TinO3n+1 series with n≠∞ have tetragonal symmetry and space group 14/mmm. These phases are formed by inserting a rock-salt SrO layer every n SrTiO3 perovskites, resulting in a successive perovskite blocks being mutually sheared by [1/2,1/2,0] (Fig. 1).Previously, the n = 1 - 3 members of this series have been made in polycrystalline form using solid state synthesis methods. Attempts to synthesize intermediate members (4≤n<∞) have been unsuccessful and resulted in mixed phase samples. Fortunately, significant advancement in epitaxial growth techniques makes it possible to control the synthesis of a wide variety of homologous oxide crystal systems. In the present work, thin films of the Srn+1TinO3n+1, RP series with n = 1 - 5 have been synthesized using reactive molecular beam epitaxy (MBE).

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Nath, Narayan Chandra Deb, Gavindasamy Murugadoss, and Jae-Joon Lee. "Large-Scale Production of APbX3 Perovskites in Powder Form with High Stability." Nanoscience and Nanotechnology Letters 10, no. 8 (August 1, 2018): 1025–34. http://dx.doi.org/10.1166/nnl.2018.2678.

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Zhang, Yaheng, Chao Fan, Jianghong Tang, Gaoming Huang, Xinfa Qiang, Yu Fu, Wenjuan Zhou, Juan Wu, and Shouqiang Huang. "Systematic Microwave-Assisted Postsynthesis of Mn-Doped Cesium Lead Halide Perovskites with Improved Color-Tunable Luminescence and Stability." Nanomaterials 12, no. 15 (July 23, 2022): 2535. http://dx.doi.org/10.3390/nano12152535.

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The metal doping at the Pb2+ position provides improved luminescence performance for the cesium lead halide perovskites, and their fabrication methods assisted by microwave have attracted considerable attention due to the advantages of fast heating and low energy consumption. However, the postsynthetic doping strategy of the metal-doped perovskites driven by microwave heating still lacks systematic research. In this study, the assembly of CsPbBr3/CsPb2Br5 with a strong fluorescence peak at 523 nm is used as the CsPbBr3 precursor, and through the optimization of the postsynthetic conditions such as reaction temperatures, Mn2+/Pb2+ feeding ratios, and Mn2+ sources, the optimum Mn2+-doped product (CsPb(Cl/Br)3:Mn) is achieved. The exciton fluorescence peak of CsPb(Cl/Br)3:Mn is blueshifted to 437 nm, and an obvious fluorescence peak attributing to the doped Mn2+ ions at 597 nm is obtained. Both the CsPbBr3 precursor and CsPb(Cl/Br)3:Mn have high PLQY and stability because there are CsPb2Br5 microcubic crystals to well disperse and embed the CsPbBr3 nanocrystals (NCs) in the precursor, and after Mn2+-doping, this structure is maintained to form CsPb(Cl/Br)3:Mn NCs on the surface of their microcrystals. The exploration of preparation parameters in the microwave-assisted method provides insights into the enhanced color-tunable luminescence of the metal-doped perovskite materials.

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Yang, Jien, Songhua Chen, Jinjin Xu, Qiong Zhang, Hairui Liu, Zhiyong Liu, and Mingjian Yuan. "A Review on Improving the Quality of Perovskite Films in Perovskite Solar Cells via the Weak Forces Induced by Additives." Applied Sciences 9, no. 20 (October 17, 2019): 4393. http://dx.doi.org/10.3390/app9204393.

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Perovskite solar cells (PSCs) employing organic-inorganic halide perovskite as active layers have attracted the interesting of many scientists since 2009. The power conversion efficiency (PCE) have pushed certified 25.2% in 2019 from initial 3.81% in 2009, which is much faster than that of any type of solar cell. In the process of optimization, many innovative approaches to improve the morphology of perovskite films were developed, aiming at elevate the power conversion efficiency of perovskite solar cells (PSCs) as well as long-term stability. In the context of PSCs research, the perovskite precursor solutions modified with different additives have been extensively studied, with remarkable progress in improving the whole performance. In this comprehensive review, we focus on the forces induced by additives between the cations and anions of perovskite precursor, such as hydrogen bonds, coordination or some by-product (e.g., mesophase), which will lead to form intermediate adduct phases and then can be converted into high quality films. A compact uniform perovskite films can not only upgrade the power conversion efficiency (PCE) of devices but also improve the stability of PSCs under ambient conditions. Therefore, strategies for the implementation of additives engineering in perovskites precursor solution will be critical for the future development of PSCs. How to manipulate the weak forces in the fabrication of perovskite film could help to further develop high-efficiency solar cells with long-term stability and enable the potential of future practical applications.

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Ouyang, Zhenyu, Ninghao Zhou, Meredith G. McNamee, Liang Yan, Olivia F. Williams, Zijian Gan, Ran Gao, Wei You, and Andrew M. Moran. "Origin of layered perovskite device efficiencies revealed by multidimensional time-of-flight spectroscopy." Journal of Chemical Physics 156, no. 8 (February 28, 2022): 084202. http://dx.doi.org/10.1063/5.0072976.

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Mixtures of layered perovskite quantum wells with different sizes form prototypical light-harvesting antenna structures in solution-processed films. Gradients in the bandgaps and energy levels are established by concentrating the smallest and largest quantum wells near opposing electrodes in photovoltaic devices. Whereas short-range energy and charge carrier funneling behaviors have been observed in layered perovskites, our recent work suggests that such light-harvesting processes do not assist long-range charge transport due to carrier trapping at interfaces between quantum wells and interstitial organic spacer molecules. Here, we apply a two-pulse time-of-flight technique to a family of layered perovskite systems to explore the effects that interstitial organic molecules have on charge carrier dynamics. In these experiments, the first laser pulse initiates carrier drift within the active layer of a photovoltaic device, whereas the second pulse probes the transient concentrations of photoexcited carriers as they approach the electrodes. The instantaneous drift velocities determined with this method suggest that the rates of trap-induced carrier deceleration increase with the concentrations of organic spacer cations. Overall, our experimental results and model calculations suggest that the layered perovskite device efficiencies primarily reflect the dynamics of carrier trapping at interfaces between quantum wells and interstitial organic phases.

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Kim, Dongyeon, Seungsoo Jang, Seeun Oh, and Kang Taek Lee. "Bimetal-Doped BaCoO_3-δ Materials As Oxygen Electrodes for High-Performance Protonic Ceramic Electrochemical Cells." ECS Meeting Abstracts MA2022-02, no. 47 (October 9, 2022): 1789. http://dx.doi.org/10.1149/ma2022-02471789mtgabs.

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Protonic ceramic electrochemical cells (PCECs) have received considerable attention owing to their ability to reversibly convert chemical fuels into electricity and vice versa on demand at low temperatures below 600 °C. Unfortunately, the sluggish kinetics at the oxygen electrode induces the poor reaction activity and stability of cells. Hence, the development of a highly active oxygen electrode is greatly needed for the realization of high-performance PCECs. One effective strategy is to bimetal doping high-valence cations in the SrCoO3- 𝛿 lattice to improve the oxygen permeability and stability of the oxygen electrode. However, Sr-containing perovskites still have durability issues related to Sr segregation under water vapor conditions. In this regard, BaCoO3- 𝛿 based perovskite oxides have attracted attention as Sr-free oxygen electrodes for many reasons such as large ionic radii, low electronegativity, and cost-effective of Ba compared to that of Sr. Inspired by recent studies, we present bimetal-doped BaCoO3- 𝛿 based perovskite oxides as a highly active and durable oxygen electrode. The bimetal doping strategy of high valence cations in BaCoO3- 𝛿 lattice can be expected to effectively stabilize the structure to form a cubic perovskite phase as well as a higher oxygen vacancy concentration. Through this work, we showcase the bimetal-doping strategy for BaCoO3- 𝛿 perovskite oxides as an oxygen electrode for high-performance PCECs.

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Hu, Qichuan, Hailong Yu, Shunfa Gong, Qiuju Han, and Wenzhi Wu. "One-dimensional luminescent tetrabutylammonium lead halide perovskite synthesized with deep eutectic solvents." Journal of Materials Chemistry C 10, no. 15 (2022): 6002–8. http://dx.doi.org/10.1039/d2tc00382a.

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The mixture of TBAX powder and PbX2 powder were heated and then naturally cooled to form DES-TBAX/PbX2 for the first time, and 1D(TBA)4Pb5Br14−xClx·HBr(Cl)·2H2O and TBAPbI3 perovskites were formed in the DES-TBAX/PbX2 with good thermal stability.

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Zhai, Shang, Jimmy Rojas, Nadia Ahlborg, Kipil Lim, Chung Hon Michael Cheng, Chenlu Xie, Michael F. Toney, In-Ho Jung, William C. Chueh, and Arun Majumdar. "High-capacity thermochemical CO2 dissociation using iron-poor ferrites." Energy & Environmental Science 13, no. 2 (2020): 592–600. http://dx.doi.org/10.1039/c9ee02795e.

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Dissociation of CO₂ to form CO can play a key role in decarbonizing our energy system. Fe-poor ferrites exhibit significantly higher capacity for thermochemical CO₂ dissociation than state-of-the-art materials such as ceria and perovskites.

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Ghobadi, Mahdi, Gerhard P. Brey, Axel Gerdes, Heidi E. Höfer, and Jörg Keller. "Accessories in Kaiserstuhl carbonatites and related rocks as accurate and faithful recorders of whole rock age and isotopic composition." International Journal of Earth Sciences 111, no. 2 (December 9, 2021): 573–88. http://dx.doi.org/10.1007/s00531-021-02130-9.

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AbstractThe accessories perovskite, pyrochlore, zirconolite, calzirtite and melanite from carbonatites and carbonate-rich foidites from the Kaiserstuhl are variously suited for the in situ determination of their U–Pb ages and Sr, Nd- and Hf-isotope ratios by LA-ICP-MS. The 143Nd/144Nd ratios may be determined precisely in all five phases, the 176Hf/177Hf ratios only in calzirtite and the 87Sr/86Sr ratios in perovskites and pyrochlores. The carbonatites and carbonate-rich foidites belong to one of the three magmatic groups that Schleicher et al. (1990) distinguished in the Kaiserstuhl on the basis of their Sr, Nd and Pb isotope ratios. Tephrites, phonolites and essexites (nepheline monzogabbros) form the second and limburgites (nepheline basanites) and olivine nephelinites the third. Our 87Sr/86Sr isotope data from the accessories overlap with the carbonatite and olivine nephelinite fields defined by Schleicher et al. (1990) but exhibit a much narrower range. These and the εNd and εHf values plot along the mantle array in the field of oceanic island basalts relatively close to mid-ocean ridge basalts. Previously reported K–Ar, Ar–Ar and fission track ages for the Kaiserstuhl lie between 16.2 and 17.8 Ma. They stem entirely from the geologically older tephrites, phonolites and essexites. No ages existed so far for the geologically younger carbonatites and carbonate-rich foidites except for one apatite fission track age (15.8 Ma). We obtained precise U–Pb ages for zirconolites and calzirtites of 15.66, respectively 15.5 Ma (± 0.1 2σ) and for pyrochlores of 15.35 ± 0.24 Ma. Only the perovskites from the Badberg soevite yielded a U–P concordia age of 14.56 ± 0.86 Ma while the perovskites from bergalites (haüyne melilitites) only gave 206Pb/238U and 208Pb/232Th ages of 15.26 ± 0.21, respectively, 15.28 ± 0.48 Ma. The main Kaiserstuhl rock types were emplaced over a time span of 1.6 Ma almost 1 million years before the carbonatites and carbonate-rich foidites. These were emplaced within only 0.32 Ma.

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Qaid, Saif M. H., Hamid M. Ghaithan, Bandar Ali Al-Asbahi, and Abdullah S. Aldwayyan. "Ultra-Stable Polycrystalline CsPbBr3 Perovskite–Polymer Composite Thin Disk for Light-Emitting Applications." Nanomaterials 10, no. 12 (November 29, 2020): 2382. http://dx.doi.org/10.3390/nano10122382.

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Organic–inorganic halide organometal perovskites have demonstrated very promising performance in optoelectronic applications, but their relatively poor chemical and colloidal stability hampers the further improvement of devices based on these materials. Perovskite material engineering is crucial for achieving high photoluminescence quantum yields (PLQYs) and long stability. Herein, these goals are attained by incorporating bulk-structure CsPbBr3, which prevents colloidal degradation, into polymethyl methacrylate (PMMA) polymer in thin-disk form. This technology can potentially realize future disk lasers with no optical and structural contributions from the polymer. The polycrystalline CsPbBr3 perovskite particles were simply obtained by using a mechanical processing technique. The CsPbBr3 was then incorporated into the PMMA polymer using a solution blending method. The polymer enhanced the PLQYs by removing the surface trap states and increasing the water resistance and stability under ambient conditions. In our experimental investigation, the CsPbBr3/PMMA composites were extraordinarily stable and remained strongly luminescent after water immersion for three months and air exposure for over one year, maintaining 80% of their initial photoluminescence intensity. The CsPbBr3/PMMA thin disk produced amplified spontaneous emission for a long time in air and for more than two weeks in water.

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Popuri, Srinivasa R., Debbie Redpath, Gavin Chan, Ronald I. Smith, Oscar Cespedes, and Jan-Willem G. Bos. "Antisite-disorder, magnetic and thermoelectric properties of Mo-rich Sr2Fe1−yMo1+yO6 (0 ≤ y ≤ 0.2) double perovskites." Dalton Transactions 44, no. 23 (2015): 10621–27. http://dx.doi.org/10.1039/c4dt03307h.

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A-site deficiency does not survive in Sr_2−xFeMoO₆ and instead Mo-rich Sr₂Fe_1−yMo_1+yO₆ perovskites, characterised by the gradual disordering of Fe and Mo, form.

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Boffa Ballaran, Tiziana, Kanchana Kularatne, and Reidar Trønnes. "High-pressure structural behaviour of CaIrO3polymorphs." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C267. http://dx.doi.org/10.1107/s2053273314097320.

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The two known polymorphs of CaIrO3 crystallize int the orthorhombic space groups Pbnm and Cmcm. These compounds have been the focus of much research in the Earth sciences community because they are isostructural with MgSiO3 perovskite and post-perovskite structures which are likely the most abundant minerals in the Earth's lower mantle. CaIrO3 post-perovskite is stable at ambient conditions and transforms at 1-3 GPa and at temperatures above 13500C to the CaIrO3 perovskite structure providing an ideal low pressure and low temperature analogue for the MgSiO3 perovskite to post-perovskite phase transformation which occurs at the extreme conditions of 125 GPa and 2500 K. However, in order to assess whether the CaIrO3 compounds can be used as analogues of MgSiO3 phases, a correct knowledge of their atomic structures and their response to changes in pressure and temperature is essential. In this study the structural behavior of both CaIrO3 polymorphs has been investigated using single-crystal X-ray diffraction at different pressures up to 10 GPa. The orthorhombic distortion of CaIrO3 perovskite derives from the cubic perovskite aristotype by tilting of the octahedral units. These tilts are very large and their variation with pressure is clearly different from the tilting reported for other Ca-oxide perovskites giving rise to a much stiffer structure. The CaIrO3 post-perovskite phase has a layered structure consisting of alternating sheets of Ca atoms and distorted IrO6 octahedra which share edges to form rows running parallel to [100]. With increasing pressure the octahedral tilting remains practically constant and compression of the post-perovskite structure occurs as a result of compression of Ca layers. With increasing temperature, instead, the octahedral tilting increases giving rise to smaller distances between oxygens of adjacent octahedra whose repulsion likely causes the transformation to the CaIrO3 perovskite structure.

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Masawa, Salma Maneno, Jihong Li, Chenxu Zhao, Xiaolong Liu, and Jianxi Yao. "0D/2D Mixed Dimensional Lead-Free Caesium Bismuth Iodide Perovskite for Solar Cell Application." Materials 15, no. 6 (March 16, 2022): 2180. http://dx.doi.org/10.3390/ma15062180.

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Bismuth-based perovskites are potentially a promising alternative for lead-free perovskites. During bond formation, however, trivalent ions on Cs3Bi2I9 with CsI/BiI3 ratio of 1.5/1 form 0D-neutral charged compounds with higher bandgap (>2.0 eV) and poor absorption capacity. Mixed 0/2-dimensional structures are potentially suitable substitutes due to their low bandgap. So far, the reported CsI/BiI3 ratios for 0D/2D structures are 1:1, 1:2 and 1:3. Herein, a new ratio of 1/1.5 is reported. Caesium bismuth iodide at a ratio of CsI/BiI3 of 1/1.5 was synthesised using a one-step processing method with/without solvent vapour annealing. During solvent annealing, a 1/4 (v/v) mixture of DMF/methanol was used as a solvent. The crystal structure formed at a ratio of 1/1.5 is more similar to 1.5/1 than to 1/3. The XRD pattern revealed additional characteristics peaks at 009, 012, 209 and 300, indicating the growth of another phase. The formed heterogeneous mixed 0D/2D structure has an extended light absorption capacity greater than 720 nm. Solvent vapour annealing improved film morphology by enhancing grain size and packing density. When cells with and without solvent vapour annealing are compared, the power conversion efficiency of caesium bismuth iodide increases from 0.26% without solvent annealing to 0.98% with solvent vapour annealing. This study establishes a new route for future research on crystal configuration, nomenclature, film and morphology, quality tailoring and applications toward the goal of lead-free perovskite solar cells.

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Shahed, N. A., M. K. Hossain, S. Khanom, M. Nishat, M. J. Alam, M. A. Hossain, and F. Ahmed. "Optical and Magnetic Properties of Oxygen-Deficient Ba2MMoO6−μ (M=Mn, Fe and μ=0, 0.5, 1.0) in a Monoclinic Phase: A First-Principles Study." SPIN 10, no. 03 (August 19, 2020): 2050023. http://dx.doi.org/10.1142/s201032472050023x.

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Double perovskites are usually strongly correlated electronic systems that offer many multifunctional properties and are most commonly formed in the monoclinic crystal phase. In this study, we used a first-principles DFT approach in studying the optical and magnetic aspects of Ba2MMoO6 ([Formula: see text], Fe) double perovskite structures in a new monoclinic phase in both their pure and oxygen-deficient form and compared it to their natural cubic phase. The structural parameters of our structures were consistent with the available experimental data of the similar Ca2MMoO6 compounds. The optical analysis suggests a high dielectric function for both compounds in their pure and defected state. The addition of defects increases the absorption of photons near the visible spectra. We also found the structures to be half-metallic, with a reduction of magnetic strength and half-metallic gaps when oxygen defects are added to the structure. These features suggest a possible application in the optoelectronics and spintronics industry, even when the crystal structures have oxygen vacancies.

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Nakatsuka, Akihiko, Hiroshi Arima, Osamu Ohtaka, Keiko Fujiwara, and Akira Yoshiasa. "Crystal structure of SrGeO3in the high-pressure perovskite-type phase." Acta Crystallographica Section E Crystallographic Communications 71, no. 5 (April 18, 2015): 502–4. http://dx.doi.org/10.1107/s2056989015007264.

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Single crystals of the SrGeO3(strontium germanium trioxide) high-pressure phase have been synthesized successfully at 6 GPa and 1223 K. The compound crystallizes with the ideal cubic perovskite-type structure (space groupPm-3m), which consists of a network of corner-linked regular GeO6octahedra (point-group symmetrym-3m), with the larger Sr atoms located at the centers of cavities in the form of SrO12cuboctahedra (point-group symmetrym-3m) in the network. The degrees of covalencies included in the Sr—O and the Ge—O bonds calculated from bond valences are 20.4 and 48.9%, respectively. Thus, the Ge—O bond of the GeO6octahedron in the SrGeO3perovskite has a strong covalency, comparable to those of the Si—O bonds of the SiO4tetrahedra in silicates with about 50% covalency. The thermal vibrations of the O atoms in the title compound are remarkably suppressed in the directions of the Ge—O bonds. This anisotropy ranks among the largest observed in stoichiometric cubic perovskites.

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Quilty, Calvin D., Maxim Avdeev, Jeremy D. Driskell, and Eirin Sullivan. "Structural characterization and photoluminescence in the rare earth-free oxy-fluoride anti-perovskites Sr3−xBi2x/3AlO4F and Sr3−xBi2x/3GaO4F." Dalton Transactions 46, no. 12 (2017): 4055–65. http://dx.doi.org/10.1039/c7dt00310b.

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The oxy-fluoride anti-perovskites Sr_3−xBi_2x/3AlO₄F and Sr_3−xBi_2x/3GaO₄F form rare earth-free phosphors where Bi³⁺ions preferentially occupy the ten coordinate Sr(1) site.

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Underwood, Cameron C. L., J. David Carey, and S. Ravi P. Silva. "Influence of A site cation on nonlinear band gap dependence of 2D Ruddlesden–Popper A2Pb1−xSnxI4 perovskites." Materials Advances 2, no. 15 (2021): 5254–61. http://dx.doi.org/10.1039/d1ma00491c.

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Ruddlesden–Popper phase (RPP) perovskites of the form A1_n−1A2₂B_nX_3n+1 show great promise in stable photovoltaic (PV) devices or as light emitting diodes (LEDs), by allowing for the mixing of 2D materials and tuning of the band gap over a large energy range.

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Warren, Michele C., Graeme J. Ackland, Bijaya B. Karki, and Stewart J. Clark. "Phase transitions in silicate perovskites from first principles." Mineralogical Magazine 62, no. 5 (October 1998): 585–98. http://dx.doi.org/10.1180/002646198547981.

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AbstractThe equilibrium structures of cubic, tetragonal and orthorhombic phases of magnesium silicate perovskite are found from first principles electronic structure calculations. Zone centre and zone boundary phonons of each phase are also calculated from ab initio forces from finite displacments, and phase transitions between the phases are analysed in terms of phonon instabilities, and coupling between modes. Both the cubic and tetragonal phases have strongly unstable modes dominated by rotation of the SiO6 octahedra, which freeze in to ultimately form the orthorhombic phase. First priniciples molecular dynamics simulations at finite temperatures are used to further investigate the stability of the intermediate tetragonal phase and the coupling between participating phonon modes. The implications for a transition temperature between orthorhombic and tetragonal phases are discussed.

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Nikolaou, Pavlos, Anastasia Vassilakopoulou, Dionysios Papadatos, Emmanuel Topoglidis, and Ioannis Koutselas. "A chemical sensor for CBr4 based on quasi-2D and 3D hybrid organic–inorganic perovskites immobilized on TiO2 films." Materials Chemistry Frontiers 2, no. 4 (2018): 730–40. http://dx.doi.org/10.1039/c7qm00550d.

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It is possible that methylamine by being reduced could escape to the environment, thus, forcing the remaining perovskite to form other perovskite-like chemical moieties based on low dimensional arrangement of PbBr₆ octahedra, rather than PbBr₂.

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RAVEAU, B., M. M. BOREL, A. LECLAIRE, and A. GRANDIN. "NIOBIUM PHOSPHATE BRONZES — STRUCTURAL RELATIONSHIPS WITH PURE OCTAHEDRAL OXYGEN TUNGSTEN BRONZES." International Journal of Modern Physics B 07, no. 23n24 (October 30, 1993): 4109–43. http://dx.doi.org/10.1142/s0217979293003590.

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The phosphate niobium bronzes form a large family of structures characterized by pentagonal or hexagonal tunnels. The host lattices of these oxides, involving a mixed valency of niobium Nb(V)-Nb(IV) are described here. The close relationships with pure octahedral structures, mainly perovskites, hexagonal tungsten bronzes (HTB) and tetragonal tungsten bronzes (TTB), and K 3 Nb 8 O 21 are studied.

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Dai, Jun, Liang Ma, Minggang Ju, Jinsong Huang, and Xiao Cheng Zeng. "In- and Ga-based inorganic double perovskites with direct bandgaps for photovoltaic applications." Physical Chemistry Chemical Physics 19, no. 32 (2017): 21691–95. http://dx.doi.org/10.1039/c7cp03448b.

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Double perovskites in the form of A₂B′B′′X₆ (A = Cs, B′ = Cu, Ag, Au, B′′ = In, Ga, X = Cl, Br, I) are examined for photovoltaic applications. Only Cs₂AgInBr₆ is predicted to be thermodynamically stable with a direct band gap in the range of 0.9–1.6 eV.

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Duan, Zonghui, Guangren Na, Shixun Wang, Jiajia Ning, Bangyu Xing, Fei Huang, Arsenii S. Portniagin, Stephen V. Kershaw, Lijun Zhang, and Andrey L. Rogach. "Proton Transfer‐Driven Modification of 3D Hybrid Perovskites to Form Oriented 2D Ruddlesden–Popper Phases." Small Science 2, no. 3 (December 23, 2021): 2100114. http://dx.doi.org/10.1002/smsc.202100114.

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Akinpelu, Akinwumi, Oluwole E. Oyewande, Adaeze, Arijaje T. Emuobor, C. Olawole, I. Ogunrionola, and Ogundile O. Paul. "Analytical Form of Sputtering in Relation to Surface Binding Energy for Different Types of Perovskites." Journal of Physics: Conference Series 1299 (August 2019): 012022. http://dx.doi.org/10.1088/1742-6596/1299/1/012022.

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WANG, DAWEI, JEEVAKA WEERASINGHE, ABDULLAH ALBARAKATI, and L. BELLAICHE. "TERAHERTZ DIELECTRIC RESPONSE AND COUPLED DYNAMICS OF FERROELECTRICS AND MULTIFERROICS FROM EFFECTIVE HAMILTONIAN SIMULATIONS." International Journal of Modern Physics B 27, no. 22 (August 12, 2013): 1330016. http://dx.doi.org/10.1142/s0217979213300168.

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Ferroelectric and multiferroic materials form an important class of functional materials. Over the last 20 years, first-principles-based effective Hamiltonian approaches have been successfully developed to simulate these materials. In recent years, effective Hamiltonian approaches were combined with molecular dynamics (MD) methods to investigate terahertz dynamical properties of various perovskites. With this combination, a variety of ferroelectric and multiferroic materials, including BaTiO 3, Ba(Sr, Ti)O 3, Pb(Zr, Ti)O 3, BiFeO 3 and SrTiO 3 bulks and films have been simulated, which led to the understanding of complex phenomena and discovery of novel effects. In this paper we first provide technical details about effective Hamiltonians and MD simulation method. Then, we present applications of the combination of these two techniques to different perovskites. Finally, we briefly discuss possible future directions of this approach.

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Journal articles on the topic 'Perovskites form'

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