相关论文: Revealing the Low Temperature Phase of FAPbI$_3$ u…
Formamidinium-lead-iodide (FAPbI$_3$) has established itself as the state of the art for high solar-energy conversion efficiency in perovskite-based solar cells. At room temperature, FAPbI$_3$ has a peculiar crystal structure with…
The optoelectronic properties and ultimately photovoltaic performance of hybrid lead halide perovskites, is inherently related to the dynamics of the organic cations. Here we report on the dynamics of the formamidinium (FA) cation in FAPbX3…
The family of organic-inorganic tri-halide perovskites including MA (MethylAmmonium)PbI$_{3}$, MAPbI$_{3-x}$Cl$_{x}$, FA (FormAmidinium)PbI$_{3}$ and FAPbBr$_{3}$ are having a tremendous impact on the field of photovoltaic cells due to…
Using muon spin relaxation ($\mu$SR) measurements on formamidinium lead iodide [FAPbI$_3$, where FA denotes HC(NH$_2)_2$] we show that, among the five structurally distinct phases of FAPbI$_3$ exhibited through two different temperature…
Fundamentally understanding the lattice dynamics and microscopic mechanisms of thermal transport in cubic hybrid organic-inorganic perovskites remains elusive, primarily due to their strong anharmonicity and frequent phase transitions. In…
Hybrid lead halide perovskites exhibit a delicate interplay between average crystallographic symmetry, local structural disorder and A-site orientational dynamics, giving rise to unusual vibrational and electronic behaviour. Here, we…
The phase transitions between the various polymorphs of FAPbI$_{3}$ (FAPI, FA = formamidinium CH(NH$_{2}$)$_{2}^+$) are studied by anelastic, dielectric and X--ray diffraction measurements on samples pressed from $\delta -$FAPI (2H phase)…
Mixed-anion mixed-cation perovskites with (FAPbI$_3$)$_{1-x}$(MAPbBr$_3$)$_x$ composition have allowed record efficiencies in photovoltaic solar cells, but their atomic-scale behaviour is not well understood yet, in part because their…
Small cations such as guanidinium and cesium can act as templating cations to form low dimensional phases (2D, 1D, 0D) in the case of excess of organic halides. However, such phases with the widely used formamidinium (FA+) cation have not…
Among the hybrid metal-organic perovskites for photovoltaic applications FAPbI_3 (FAPI) has the best performance regarding efficiency and the worst regarding stability, even though the reports on its stability are highly contradictory. In…
This research explores how temperature influences the optical characteristics of Cubic Methylammonium Tin Iodide (CH$_3$NH$_3$SnI$_3$), a material showing great promise for solar cell technology. The variations in the optical absorption…
Methylammonium lead iodide (CH3NH3PbI3) based solar cells have shown impressive power conversion efficiencies of above 20%. However, the microscopic mechanism of the high photovoltaic performance is yet to be fully understood. Particularly,…
FAPbI3, as a typical hybrid organic-inorganic perovskite, has attracted considerable interest due to its band gap suitable for visible light absorption and good thermal stability. A barrier to the use of FAPbI3 in commercial, stable devices…
Boron phosphide (BP) is a (super)hard semiconductor constituted of light elements, which is promising for high demand applications at extreme conditions. The behavior of BP at high temperatures and pressures is of special interest but is…
The Fermi-Hubbard model describes ultracold fermions in an optical lattice and exhibits antiferromagnetic long-ranged order below the N\'{e}el temperature. However, reaching this temperature in the lab has remained an elusive goal. In other…
Halide perovskite (HaP) semiconductors are revolutionizing photovoltaic (PV) solar energy conversion by showing remarkable performance of solar cells made with esp. tetragonal methylammonium lead tri-iodide (MAPbI3). In particular, the low…
The crystal structure of barium-germanium clathrate Ba6Ge25 was studied using neutron powder diffraction in the temperature range 20-300K. The compound was found to be cubic (S.G. P4_1 23) in the entire temperature range. However, the…
Co3Si was recently reported to exhibit remarkable magnetic properties in the nanoparticle form [Appl. Phys. Lett. 108, 152406 (2016)], yet better understanding of this material is to be promoted. Here we report a study on the crystal…
The lower mantle of Earth, characterized by pressures of 24-127 GPa and temperatures of 1900-2600 K, is still inaccessible to direct observations. In this work, we investigate by first principles the stability, phase diagram, elastic…
Materials underpin modern technologies, from energy harvesting, storage, and conversion to information and communication technologies. Their functionality is often governed by the interplay between competing phases, as thermodynamic…