Search results for "PEROVSKITE"
showing 10 items of 458 documents
Light-Induced Formation of Pb3+Paramagnetic Species in Lead Halide Perovskites
2018
Hybrid halide perovskites are soft materials processed at room temperature, revolutionary players in the photovoltaic field. Nowadays, investigation of the nature and role of defects is seen as one of the key challenges toward full comprehension of their behavior and achievement of high device stability under working conditions. We reveal the reversible generation, under illumination, of paramagnetic Pb3+ defects in CH3NH3PbI3, synthesized in ambient conditions, induced by the presence of Pb-O defects in the perovskite structure that may trap photogenerated holes, possibly mediated by the concomitant oxidation and migration of ions. According to the mechanism that we hypothesize, one charge…
Screening Ferroelastic Transitions in Switchable Cyano-Bridged Perovskites: [CH3C(NH2)2]2[KM(CN)6], M = Cr3+, Fe3+, Co3+. Crystal Structure Character…
2019
Here we report the dynamics of organic cations as guest molecules in the novel perovskite host framework. The novel switchable crystals from the coordination family [CH3C(NH2)2]2[KB″(CN)6] were con...
Aluminium distribution in an Earth's non–primitive lower mantle
2020
The aluminium incorporation mechanism of perovskite was explored by means of quantum mechanics in combination with equilibrium/off-equilibrium thermodynamics under the pressure-temperature conditions of the Earth's lower mantle (from 24 to 80 GPa). Earth's lower mantle was modelled as a geochemically non-primitive object because of an enrichment by 3 wt% of recycled crustal material (MORB component). The compositional modelling takes into account both chondrite and pyrolite reference models. The capacity of perovskite to host Al was modelled through an Al2O3 exchange process in an unconstrained Mg-perovskite + Mg-Al-perovskite + free-Al2O3(corundum) system. Aluminium is globally incorporate…
Understanding the Pressure Effect on the Elastic, Electronic, Vibrational, and Bonding Properties of the CeScO3 Perovskite
2020
D.E. acknowledges the financial support given by the Spanish Ministry of Science, Innovation, and Universities (MCIU) under grant nos. PID2019-106383GB-C41 and RED2018-102612-T (MALTA Consolider-Team network) and by Generalitat Valenciana under Grant Prometeo/2018/123 (EFIMAT). R.F. and A. Lobato are grateful to financial support from Spanish MCIU under grant PGC2018-094814-B-C22. We would like to thank TGCC under the allocation 2020-A0080910433 made by GENCI, the PMMS (Pôle Messin de Modélisation et de Simulation), the Tirant supercomputer (Universitat de Valencia), and the MALTA-Consolider facilities for providing us the computational resources. S.G. and M.B. also acknowledge financial su…
Proton sponge lead halides containing 1D polyoctahedral chains
2021
Hybrid one-dimensional lead halides, containing the protonated 1,8-bis(dimethylamino)naphthalene moiety (C14H19N2, monoprotonated "proton sponge"), were prepared by simple one-pot methods and investigated in terms of crystal structure, morphology, thermal stability and electronic properties. The as-precipitated (C14H19N2)PbBr3 and (C14H19N2)PbI3 species are isostructural and crystallize in the orthorhombic Pbca space group, resulting in 1D crystal phases with ([PbX3](-))(infinity) chains (built by face-sharing [PbX6] octahedra; X = Br, I), among which the (C14H19N2)(+) cations are inserted. The two compounds display complete miscibility in the solid state: both (C14H19N2)PbI2Br and (C14H19N…
Theoretical and Experimental Study of (Ba,Sr)TiO 3 Perovskite Solid Solutions and BaTiO 3 /SrTiO 3 Heterostructures
2019
This study was supported by the ERA-NET HarvEnPiez project. The authors would like to thank their national funding agencies (Latvian State Education Development Agency, Slovenian Ministry of Higher Education, Science and Technology, Romanian National Authority for Scientific Research and Innovation, CCCDI-UEFISCDI, project number 49/2016 within PNCDI III – M-ERA NET Program).
Charge injection and trapping at perovskite interfaces with organic hole transporting materials of different ionization energies
2019
The extraction of photogenerated holes from CH3NH3PbI3 is crucial in perovskite solar cells. Understanding the main parameters that influence this process is essential to design materials and devices with improved efficiency. A series of vacuum deposited hole transporting materials (HTMs) of different ionization energies, used in efficient photovoltaic devices, are studied here by means of femtosecond transient absorption spectroscopy. We find that ultrafast charge injection from the perovskite into the different HTMs (<100 fs) competes with carrier thermalization and occurs independently of their ionization energy. Our results prove that injection takes place from hot states in the valence…
Perovskite nanoparticles : synthesis, properties, and novel applications in photovoltaics and LEDs
2018
Solar cells and light-emitting diodes (LEDs) based on metal-halide perovskites are transitioning from promising performers to direct competitors to well-established technologies, with cost-effectiveness as a strong advantage. Nanostructured perovskites have yielded record LEDs due to their higher versatility in the local management of charge carriers, which has enabled photoluminescence quantum yields (PLQYs) close to 100%. However, these perovskite nanostructures are yet to be fully exploited in other applications such as photovoltaics, where they can also present competitive advantages as they enable feasible routes to surpass the Shockley–Queisser limit by means of multiexciton generatio…
Ab initio calculations of ABO3 perovskite (001), (011) and (111) nano-surfaces, interfaces and defects
2020
We carried out ab initio calculations for technologically important ABO3 perovskite, such as, SrTiO3, BaTiO3, SrZrO3 and PbZrO3 (001), (011) and (111) nano-surfaces, interfaces and bulk [Formula: see text]-centers. For SrTiO3, BaTiO3, SrZrO3 and PbZrO3 (001) nano-surfaces, as a rule, all first surface layer atoms relax inward, whereas all second layer atoms relax outward, and, typically, all third surface layer atoms, again, relax inward. Calculated (001) surface energies for SrTiO3, BaTiO3, SrZrO3 and PbZrO3 perovskites are almost equal for both BO2 and AO-terminations, and always smaller than the (011) and (111) surface energies. We discussed the results of our ab initio calculations dea…
Ab initio simulation of (Ba,Sr)TiO3 and (Ba,Ca)TiO3 perovskite solid solutions
2019
Abstract The results of ab initio (first-principles) computations of structural, elastic and piezoelectric properties of Ba(1−x)SrxTiO3 (BSTO) and Ba(1−x)CaxTiO3 (BCTO) perovskite solid solutions are presented, discussed and compared. Calculations are performed with the CRYSTAL14 computer code within the linear combination of atomic orbitals (LCAO) approximation, using advanced hybrid functionals of the density-functional-theory (DFT). Supercell model allows us to simulate solid solutions with different chemical compositions (x = 0, 0.125 and 0.25) within ferroelectric tetragonal phases (x