Proton Irradiation on Halide Perovskites: Numerical Calculations.

The results of numerical SRIM and SCAPS calculations for the ionization, displacement and heating of hybrid perovskites under the influence of protons (E = 0.15, 3.0 and 18 MeV) are presented and show that the lowest transfer energy is demonstrated by the MAPbI, FAPbBr and FAPbI compounds, which represent the greatest potential for use as solar cells in space devices.

The Stability of Hybrid Perovskites with UiO-66 Metal-Organic Framework Additives with Heat, Light, and Humidity.

This study is devoted to investigating the stability of metal-organic framework (MOF)-hybrid perovskites consisting of CHNHPbI (MAPbI) and UiO-66 without a functional group and UiO-66 with different COOH, NH,and F functional groups under external influences including heat, light, and humidity. By conducting crystallinity, optical, and X-ray photoelectron spectra (XPS) measurements after long-term aging, all of the prepared MAPbI3@UiO-66 nanocomposites (with pristine UiO-66 or UiO-66 with additional functional groups) were stable to light soaking and a relative humidity (RH) of 50%. Moreover, the UiO-66 and UiO-66-(F) hybrid perovskite films possessed a higher heat tolerance than the other two UiO-66 with the additional functional groups of NH and COOH.

Unveiling the Atomic and Electronic Structure of Stacked-Cup Carbon Nanofibers.

We report results of comprehensive experimental exploration (X-ray photoemission, Raman and optical spectroscopy) of carbon nanofibers (CNFs) in combination with first-principles modeling. Core-level spectra demonstrate prevalence of sp2 hybridization of carbon atoms in CNF with a trace amount of carbon-oxygen bonds. The density functional theory (DFT)-based calculations demonstrated no visible difference between mono- and bilayers because σ-orbitals are related to in-plane covalent bonds.

Thermal Effects and Halide Mixing of Hybrid Perovskites: MD and XPS Studies.

Thermal effects in organo-metal halide perovskites are studied by ab initio molecular dynamics (MD) simulations performed at effective temperatures of 293 and 383 K and by X-ray photoelectron spectroscopy (XPS). We find that the cause of thermal instability in this class of perovskites is the rotation of the methylammonium (MA) groups that destroy the rigid lattice of pure compounds (MAPbI and MAPbBr). When the Pb-I lattice is initially distorted by partial replacement of the I with Cl or Br, this not only prevents formation of PbI seeds but also improves lattice flexibility and stability against the temperature-induced motion and rotation of MA groups.

XPS evidence of degradation mechanism in CHNHPbI hybrid perovskite.

In this study, we investigate the photo-/thermal degradation mechanism of hybrid perovskites by using x-ray photoelectron (XPS) valence band (VB) spectra coupling with density functional theory (DFT) calculations. Herein, CHNHPbI is respectively subjected to irradiation with visible light and annealing at an exposure of 0-1000 h. It is found from XPS survey spectra that, in both cases (irradiation and annealing), a decrease in the I:Pb ratio is observed with aging time, which unambiguously indicates the formation of PbI as the product of photo/thermal degradation.