Near Unity PLQY and High Stability of Barium Thiocyanate Based All-Inorganic Perovskites and Their Applications in White Light-Emitting Diodes

Solvent Effects on the Structural and Optical Properties of MAPbI3 Perovskite Thin Film for Photovoltaic Active Layer

Controlling the crystallinity, homogeneity, and surface morphology is an efficient method of enhancing the perovskite layer. These improvements contribute toward the optimization of perovskite film morphology for its use in high-performance photovoltaic applications. Here, different solvents will be used in order to process the perovskite precursor, to improve the interfacial contacts through generating a smooth film and uniform crystal domains with large grains. The effect that the solvent has on the optical and structural properties of spin-coated methyl ammonium lead iodide (MAPbI3) perovskite thin films prepared using a single-step method was systematically investigated. The spin-coating parameters and precursor concentrations of MAI and PbI2 were optimized to produce uniform thin films using the different solvents N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL). The effect that the solvent has on the morphology of the MAPbI3 films was examined to determine how the materials can be structurally altered to make them highly efficient for use in perovskite hybrid photovoltaic applications. Scanning electron microscopy (SEM) and X-ray diffractometry (XRD) results show that the synthesized MAPbI3 films prepared using DMSO, DMF, and GBL exhibit the best crystallinity and optical characteristics (photoluminescence (PL)), respectively, of the prepared films. The optical properties resulting from the noticeable improvement PL of the films can be clearly correlated with their crystallinity, depending on the solvents used in their preparation. The film prepared in DMSO shows the highest transmittance and the highest bandgap energy of the prepared films.

In situ siloxane passivation of colloidal lead halide perovskite via hot injection for light-emitting diodes

All-inorganic cesium lead halide perovskite (CsPbX₃; X = Cl, Br) nanocrystals (NCs) are synthesized via a modified hot injection method using 3-mercaptopropyltrimethoxysilane (MPTMS), together with oleic acid and oleylamine, for in situ passivation of the surface defects. The surface chemistry, revealed by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) techniques, shows an absence of Si-O-Si network and C-O groups on these in situ passivated CsPbX₃ NCs, denoted as InMP-CsPbX₃, which is in strong contrast to the counterpart NCs obtained via a postsynthesis exchange strategy. The x-ray diffraction (XRD) pattern indicates a lattice structure significantly strained from the cubic structure. The synthesis of these InMP-CsPbX₃ NCs is highly reproducible, and the colloids are stable in nonpolar solvents. The emission wavelength of CsPb(Cl/Br)₃ mixed halide perovskite NCs is tuned from 405 nm to 508 nm by reducing the nominal Cl/Br ratio, while the photoluminescence quantum yield (PLQY) is greatly enhanced over the whole spectral range. More importantly, the InMP-treatment is among the few strategies that are promising for electroluminescence in light-emitting diodes.

Mn4+-activated oxyfluoride K3TaOF6 red phosphor with intense zero phonon line for warm white light-emitting diodes

The intense zero phonon line (ZPL) of the Mn4+:2E→4A2 transition can further promote the color rendering and luminous efficiency for high-quality white-emitting diodes (w-LEDs). In this article, a Mn4+-activated K3TaOF6 oxyfluoride red phosphor was synthesized via a facile two-step method. Its phase and morphology were characterized by X-ray diffraction, SEM and TEM. The as-prepared K3TaOF6:Mn4+ exhibits an intense absorption of blue light and a strong emission band peaking at 628 nm with a color purity as high as 96.4%. Attributed to the distorted octahedral coordination environment of Mn4+ ions, an intense ZPL emission was detected at 620 nm. By theoretical calculation, Mn4+ ions in the K3TaOF6 host experience a strong crystal field. In addition, the temperature-dependent PL and thermoluminescence (TL) spectra suggest that thermal ionization dominates the thermal quenching phenomenon in this phosphor.

A Scoping Review of Renewable Energy, Sustainability and the Environment

The article aims to identify the latest trends in research on renewable energy, sustainability and the environment. A total of 92,873 publications from 123 Scopus sources for 2020–2021 are compared using the scoping review method. The results show that the most cited works in this sample are those by authors from the Asian region. The research of these authors focuses on the security, efficiency and reliability of separate elements in energy systems. Besides, the paper considers the problems regarding COVID disease along with the renewable energy sources, perovskite and organic solar panels, nanostructured materials and high energy density. Finally, the paper analyses applications of computer science methods in research on renewable energy, sustainability and the environment. The findings evidently show that recent advancements in computer science methods were not extensively used in the discussed research domain and give a great room for novel strategies of prognosing, simulation and processes optimisation.