Related papers: Challenges in predicting positron annihilation lif…
Vacancy defects in thin film laser ablated SrTiO3 on SrTiO3 were identified using variable energy positron annihilation lifetime measurements. Strontium vacancy related defects were the dominant positron traps and, apart from in the top ~…
We theoretically investigate lead iodide perovskites of general formula APbI$_3$ for a series of metallic cations (namely Cs$^+$, Rb$^+$, K$^+$, Na$^+$ and Li$^+$) by means of the density functional theory, GW method and Bethe-Salpeter…
A heterophase containing both the optically active $\alpha$-CsPbI$_3$ and non-active $\delta$-CsPbI$_3$ has been demonstrated as an efficient white light emitter. This has challenged the conventional perspective that non-active phases of…
Mijnarends et al. [J. Phys. Condens. Matter {\bf 10}, 10383 (1998)] contested the best existing calculations of positron annihilation rates in jellium and crystal lattices, pointing in this way at deficiencies of existing theories of…
Methylammonium lead triiodide perovskite (MAPbI3) semiconductor displays outstanding photovoltaic and light emitting properties. We address the unique behavior in which a bias voltage can be used to switch on and off the luminescence of a…
Lead-free halide double perovskites A$_{2}$M(I)M(III)X$_{6}$ have garnered significant attention in the past decade as promising alternatives to CsPbX$_{3}$ perovskites, addressing concerns related to lead toxicity and material instability.…
Positron lifetimes have been calculated in bulk and monovacancies for most of the elements of the periodic table. Self-consistent and non-self-consistent schemes have been used for the calculation of the electronic structure in the solid,…
Positron annihilation lifetime spectroscopy (PALS) and positron-electron momentum density (PEMD) studies on multilayers of PbSe nanocrystals (NCs), supported by transmission electron microscopy (TEM), show that positrons are strongly…
The low ionization energy of an $A$ site molecule is a very important factor, which determines the thermodynamical stability of $A$PbI$_3$ hybrid halide perovskites, while the size of the molecule governs the stable phase at room…
Annihilation spectra are presented for aromatic and heterocyclic ring molecules resolved as a function of incident positron energy using a trap-based positron beam. Comparisons with the vibrational mode spectra yield positron-molecule…
Lead-halide perovskite (LHP) semiconductors are emergent optoelectronic materials with outstanding transport properties which are not yet fully understood. We find signatures of large polaron formation in the electronic structure of the…
In a combined theoretical and experimental work, we investigate X-ray Absorption Near-Edge Structure (XANES) spectroscopy of the I $L_3$ and the Pb $M_5$ edges of the methylammonium lead iodide ($\textrm{MAPbI}_3$) hybrid inorganic-organic…
Layered lead halide A'2An-1PbnI3n+1 perovskites (2D LHPs) are attracting considerable attention as a more stable alternative with respect to APbI3 parent phases - a promising material for a new generation of solar cells. However, a critical…
A many-body theory approach is developed for the problem of positron-atom scattering and annihilation. Strong electron-positron correlations are included non-perturbatively through the calculation of the electron-positron vertex function.…
Positron lifetime, Photoluminescence and Hall measurements were performed to study undoped p-type gallium antimonide materials. A 314ps lifetime component, attributed to $V_{Ga}$ related defect, was identified in the positron lifetime…
Owing to their exceptional semiconducting properties, hybrid inorganic-organic perovskites show great promise as photovoltaic absorbers. In these materials, long-range diffusion of charge carriers allows for most of the photogenerated…
We make a gradient correction to a new local density approximation form of positron-electron correlation. Then the positron lifetimes and affinities are probed by using these two approximation forms based on three electronic-structure…
Halide perovskites constitute a chemically-diverse class of crystals with great promise as photovoltaic absorber materials, featuring band gaps between about 1 and 3.5 eV depending on composition. Their diversity calls for a general…
Owing to the increasing popularity of lead-based hybrid perovskites for photovoltaic (PV) applications, it is crucial to understand their defect physics and its influence on their optoelectronic properties. In this work, we simulate various…
We investigate the impact of various levels of approximation in density functional theory calculations for the structural and binding properties of the prototypical halide perovskite MAPbI$_3$. Specifically, we test how the inclusion of…