Search results for "PEROVSKITE"
showing 10 items of 458 documents
ITO top-electrodes via industrial-scale PLD for efficient buffer-layer-free semitransparent perovskite solar cells
2022
The deposition of transparent conductive oxides (TCO) usually employs harsh conditions that are frequently harmful to soft/organic underlayers. Herein, successful use of an industrial pulsed laser deposition (PLD) tool to directly deposit indium tin oxide (ITO) films on semitransparent vacuum-deposited perovskite solar cells without damage to the device stack is demonstrated. The morphological, electronic, and optical properties of the PLD deposited ITO films are optimized. A direct relation between the PLD chamber pressure and the solar cell performance is obtained. The semitransparent perovskite solar cells prepared exclusively by vacuum-assisted techniques had fill factors of 78% and exc…
Ultralow thermal conductivity in 1D and 2D imidazolium-based lead halide perovskites
2021
Low-dimensional hybrid organic–inorganic metal halide perovskites are rapidly emerging as a fascinating sub-class of the three-dimensional parent structures, thanks to their appealing charge and thermal transport properties, paired to better chemical and thermal stabilities. Extensive investigations of the thermal behavior in these systems are of paramount relevance to understand their optoelectronic and thermoelectric applications. Herein, we present a complete thermophysical characterization of imidazolium lead iodide, (IMI)PbI3, a 1D pseudo-perovskite with chains of face-sharing octahedra, and histammonium lead iodide, (HIST)PbI4, a 2D layered perovskite with corner-sharing octahedra. Up…
On the Shape-Selected, Ligand-Free Preparation of Hybrid Perovskite (CH3NH3PbBr3) Microcrystals and Their Suitability as Model-System for Single-Crys…
2021
Hybrid perovskite materials are one of the most promising candidates for optoelectronic applications, e.g., solar cells and LEDs, which can be produced at low cost compared to established materials. Although this field of research has seen a huge upsurge in the past decade, there is a major lack in understanding the underlying processes, such as shape-property relationships and the role of defects. Our aerosol-assisted synthesis pathway offers the possibility to obtain methylammonium lead bromide (MAPbBr3 ) microcrystals from a liquid single source precursor. The differently shaped particles are aligned on several substrates, without using a directing agent or other additives. The obtained …
Hybrid DFT calculations of the atomic and electronic structure for ABO3 perovskite (001) surfaces
2005
Abstract We present the results of first-principles calculations on two possible terminations of the (0 0 1) surfaces of SrTiO3, BaTiO3, and PbTiO3 perovskite crystals. Atomic structure and the electronic configurations were calculated for different 2D slabs, both stoichiometric and non-stoichiometric, using hybrid (B3PW) exchange-correlation technique and re-optimized basis sets of atomic (Gaussian) orbitals. Results are compared with previous calculations and available experimental data. The electronic density distribution near the surface and covalency effects are discussed in details for all three perovskites. Both SrTiO3 and BaTiO3 (0 0 1) surfaces demonstrate reduction of the optical …
Highly luminescent perovskite–aluminum oxide composites
2015
In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence.
Perovskite solar cells join the major league
2015
Just six years after their discovery, organolead halide perovskite solar cells have taken the lead among emergent photovoltaic (PV) technologies, thanks to the demonstration of power conversion efficiencies (PCEs) of up to 20% ( 1 , 2 ). The perovskite precursor compounds are abundant and inexpensive and can easily be converted into thin films. Perovskite photovoltaics can therefore, in principle, generate electricity at a very low cost. However, high efficiencies have been limited to very small devices. On page 944 of this issue, Chen et al. ( 3 ) report perovskite solar cells of 1 cm2 with a certified efficiency of 15%.
Radiative efficiency of lead iodide based perovskite solar cells
2014
The maximum efficiency of any solar cell can be evaluated in terms of its corresponding ability to emit light. We herein determine the important figure of merit of radiative efficiency for Methylammonium Lead Iodide perovskite solar cells and, to put in context, relate it to an organic photovoltaic (OPV) model device. We evaluate the reciprocity relation between electroluminescence and photovoltaic quantum efficiency and conclude that the emission from the perovskite devices is dominated by a sharp band-to-band transition that has a radiative efficiency much higher than that of an average OPV device. As a consequence, the perovskite have the benefit of retaining an open circuit voltage ~0.1…
Evidence for a different electronic configuration as a primary effect during compression of orthorhombic perovskites: The case of NdM3+ O3 (M=Cr, Ga)
2018
(Mg,Fe)SiO3 perovskite is the most abundant mineral of the Earth's lower mantle, and compounds with the perovskite structure are perhaps the most widely employed ceramics. Hence, they attract both geophysicists and material scientists. Several investigations attempted to predict their structural evolution at high pressure, and recent advancements highlighted that perovskites having ions with the same formal valence at both polyhedral sites (i.e., 3+:3+) define different compressional patterns when transition metal ions (TMI) are involved. In this study, in situ high-pressure synchrotron XRD measurements coupled with ab initio simulations of the electronic population of NdCrO3 perovskite are…
Magnetoelectric coupling driven by inverse magnetostriction in multiferroic BiMn3Mn4O12
2013
By means of neutron powder diffraction, we investigated the effect of the polar Bi$^{3+}$ ion on the magnetic ordering of the Mn$^{3+}$ ions in BiMn$_3$Mn$_4$O$_{12}$, the counterpart with \textit{quadruple} perovskite structure of the \textit{simple} perovskite BiMnO$_3$. The data are consistent with a \textit{noncentrosymmetric} spacegroup $Im$ which contrasts the \textit{centrosymmetric} one $I2/m$ previously reported for the isovalent and isomorphic compound LaMn$_3$Mn$_4$O$_{12}$, which gives evidence of a Bi$^{3+}$-induced polarization of the lattice. At low temperature, the two Mn$^{3+}$ sublattices of the $A'$ and $B$ sites order antiferromagnetically (AFM) in an independent manner …
Radiation defects in complex perovskite solid solutions
2014
Abstract First principles density functional theory (DFT) based modeling is performed to explore formation energies of a series of point cation and oxygen defects, Frenkel and Schottky disorder, as well as structural disorder in Ba1−xSrxCo1−yFeyO3−δ (BSCF) perovskite solid solutions. The results are compared with previous studies on a prototype SrTiO3 perovskite. It is shown that BSCF permits accommodation of a high concentration of defects and cation clusters but not antisite defects.