Enhanced Performance and Stability of Perovskite Solar Cells Through Surface Modification with Benzocaine Hydrochloride.

Current development of inverted p-i-n perovskite solar cells (PSCs), with nickel oxide as the hole transport layer, is progressing toward lower net costs, higher efficiencies, and superior stabilities. Unfortunately, the high density of defect-based traps on the surface of perovskite films significantly limits the photoelectric conversion efficiency and operational stability of perovskite solar cells. Finding cost-effective interface modifiers is crucial for the further commercial development of p-i-n PSCs.

Nitrogen Reduction to Ammonia on a Fe Nanocluster: A Computational Study of Catalysis.

The sequence of elementary steps leading to reductive ammonia formation from N and H catalyzed by a Fe cluster is studied using generalized gradient approximation density functional theory and an all-electron basis set of triple-ζ quality. The computational methods are validated by comparison to experimental data such as binding energies where possible. First, the associative and dissociative attachment of N to Fe is considered, followed by exploration of the pathways leading to distal (Fe-N-NH) and enzymatic (NFe-NH) formation of an amino group.

Redox Chemistry of the Subphases of α-CsPbIBr and β-CsPbIBr: Theory Reveals New Potential for Photostability.

The logic in the design of a halide-mixed APb(I1−xBrx)3 perovskite is quite straightforward: to combine the superior photovoltaic qualities of iodine-based perovskites with the increased stability of bromine-based perovskites. However, even small amounts of Br doped into the iodine-based materials leads to some instability. In the present report, using first-principles computations, we analyzed a wide variety of α-CsPbI2Br and β-CsPbI2Br phases, compared their mixing enthalpies, explored their oxidative properties, and calculated their hole-coupled and hole-free charged Frenkel defect (CFD) formations by considering all possible channels of oxidation.

Mechanisms of Complete Dissociation of CO on Iron Clusters.

Dissociation of CO on iron clusters was studied by using semilocal density functional theory and basis sets of triple-zeta quality. Fe , Fe , and Fe clusters were selected as the representative host clusters. When searching for isomers of Fe CO , n=2, 4 and 16 corresponding to carbon dioxide attachment to the host clusters, its reduction to O and CO, and to the complete dissociation, it was found that the total spin magnetic moments of the lowest energy states of the isomers are often quenched with respect to those of initial reagents Fe +CO .

Evolution of Ferromagnetic and Antiferromagnetic States in Iron Nitride Clusters FeN and FeN ( = 1-10).

First-principles density functional theory calculations on neutral and singly negatively and positively charged iron clusters Fe and iron nitride clusters FeN and FeN ( = 1-10) in the range of 1 ≤ ≤ 10 revealed that there is a strong competition between ferromagnetic and antiferromagnetic states especially in the FeN cluster series. This phenomenon was related to superexchange via a bridging N atom between two iron atoms in the FeN cluster series and to a double superexchange effect via a Fe atom shared by two N atoms in the FeN series. A thorough examination of the structure-energy-spin state relationships in these clusters is conducted, leading to new insights and confirmation of available experimental results on structural parameters and dissociation energetics.

Superhalogens Among 3-Metal Compounds: F, F, F, and F ( = Sc-Zn).

The ground states of the neutral and anionic tetrafluoride and hexafluoride series of 3-metal atoms from Sc to Zn were assigned by using a double-check approach in which the pure and hybrid density functional methods were interchangeably used. It was confirmed that all these neutral fluorides are superhalogens except for TiF. The electron affinities of the hexafluorides were shown to be consistently higher than those of the tetrafluorides in accordance with the superhalogen conception of the extra electron delocalization over a larger number of the electronegative ligands.

Dissociation of dinitrogen on iron clusters: a detailed study of the Fe + N case.

The coalescence of two Fe8N as well as the structure of the Fe16N2 cluster were studied using density functional theory with the generalized gradient approximation and a basis set of triple-zeta quality. It was found that the coalescence may proceed without an energy barrier and that the geometrical structures of the resulting clusters depend strongly on the mutual orientations of the initial moieties. The dissociation of N2 is energetically favorable on Fe16, and the nitrogen atoms share the same Fe atom in the lowest energy state of the Fe16N2 species.

Unravelling the Material Composition Effects on the Gamma Ray Stability of Lead Halide Perovskite Solar Cells: MAPbI Breaks the Records.

In this work, we report a comparative study of the gamma ray stability of perovskite solar cells based on a series of perovskite absorbers including MAPbI (MA = methylammonium), MAPbBr, CsFAPbI (FA = formamidinim), CsMAFAPbI, CsPbI, and CsPbBr We reveal that the composition of the perovskite material strongly affects the radiation stability of the solar cells. In particular, solar cells based on the MAPbI were found to be the most resistant to gamma rays since this perovskite undergoes rapid self-healing due to the special gas-phase chemistry analyzed with calculations. The fact that the solar cells based on MAPbI can withstand a 1000 kRad gamma ray dose without any noticeable degradation of the photovoltaic properties is particularly exciting and shifts the paradigm of research in this field toward designing more dynamic rather than intrinsically robust (e.

Solid, liquid, and interfacial properties of TiAl alloys: parameterization of a new modified embedded atom method model.

New interatomic potentials for pure Ti and Al, and binary TiAl were developed utilizing the second nearest neighbour modified embedded-atom method (MEAM) formalism. The potentials were parameterized to reproduce multiple properties spanning bulk solids, solid surfaces, solid/liquid phase changes, and liquid interfacial properties. This was carried out using a newly developed optimization procedure that combined the simple minimization of a fitness function with a genetic algorithm to efficiently span the parameter space.

Structure and properties of iron oxide clusters: From Fe6 to Fe6 O20 and from Fe7 to Fe7 O24.

Geometrical and electronic structures of the neutral and singly negatively charged Fe6 On and Fe7 Om clusters in the range of 1 ≤ n ≤ 20 and 1 ≤ m ≤ 24, respectively, are computed using density functional theory with the generalized gradient approximation. The largest clusters in the two series, Fe6 O20 and Fe7 O24 , can be described as Fe(FeO4 )5 and Fe(FeO4 )6 or alternatively as [FeO5 ](FeO3 )5 and [FeO6 ](FeO3 )6 , respectively. The Fe6 O20 and Fe7 O24 clusters possess adiabatic electron affinities (EAad ) of 5.