The study of electronic and optical properties of perovskites CH

At present, Organic-inorganic hybrid methylammonium lead halide perovskites MAPbX3 (MA= CH3NH3; X = Cl, Br) have recently attract attention scientific researchers, as a promising candidate for photovoltaic and optoelectronic devices. We have studied the electronic structures and optical properties of perovskites CH3NH3PbBr3 and CH3NH3PbCl3, using density functional theory (DFT). These physical properties are calculated by CASTEP code, such as the band structures, total density of states (TDOS), absorption coefficient, refractive index and optical conductivity. The analysis of band gap shows that these two perovskites are semiconducting materials. Calculated absorption coefficient of CH3NH3PbBr3 and CH3NH3PbCl3 shows an absorption peak around 3.87 eV and 2.04 eV, respectively. The above results provide good agreement with experimental work for optoelectronic properties of CH3NH3PbBr3 and CH3NH3PbCl3 materials

DFT study on electronic and optical properties of graphene under an external electric field

The paper investigates the electronic and optical properties of graphene, under the external electric field (Eext) according to perpendicular direction, using density functional theory (DFT). Applying the Eext to the graphene sheet modifies its electronic and optical properties, including the band gap energy, total density of states (TDOS), absorption coefficient, dielectric function, and refractive index. Graphene’s band gap is opened by the application of Eext to its structure. As a result of the effect of Eext on graphene layer, its absorption coefficient increases in the ultraviolet (UV) range and decreases in the visible range. We found that the electronic and optical properties of graphene material, can be altered by a perpendicular excitation applied to its structure

Increasing Electro-Optical Properties of Perovskite FAPbI 3 Under the Effect of Doping by Sn

The development of valuable materials for photovoltaics is occurring at a rapid pace, particularly in the area of perovskite materials. The present study examines the impact of doping on the perovskite FAPbI 3 using varying percentages of tin. The researchers utilized Density Functional Theory DFT to optimize and determine the electronic and optical properties. The CASTEP code was employed for this purpose. The outcome of this research revealed that the new material displays desirable features such as high absorbency and a low bandgap, which piques the interest of scientists to apply these materials in photovoltaic systems. It is imperative to investigate high-efficiency perovskite materials with limited or no lead content, as the lead component in FAPbI 3 , a heavy metal, can cause harm to both humans and the environment

Identification and nanoentrapment of polyphenolic phytocomplex from Fraxinus angustifolia: in vitro and in vivo wound healing potential

The aim of the present study was to elucidate the polyphenolic composition of Fraxinus angustifolia leaf and bark extracts, and to evaluate their efficacy in wound healing. Quercetin, catechin, rutin and tannic acid were identified as the main components of the extracts. In order to improve their skin bioavailability, the polyphenolic phytocomplexes were incorporated in different nanovesicles, namely ethosomes and phospholipid vesicles containing Transcutol® P (Trc) or ethylene glycol (EG). The latter had never been used before as a component of phospholipid vesicles, and it was found to play a key role in improving extract effi cacy in wound healing. Results of cryogenic transmission electron microscopy (cryo-TEM), Photon Correlation Spectroscopy (PCS) and Small-Angle X-ray Scattering (SAXS) showed that ethosomes and EG-PEVs were small, monodispersed, unilamellar vesicles, while Trc-PEVs were larger, less homogeneously dispersed and multilamellar, with a large bilayer thickness. Free extracts did not show relevant ability to protect in vitro human keratinocytes from H2O2 damages, while when entrapped in nanovesicles, they signi ficantly inhibited H2O2 stress damages, probably related to a higher level of cell uptake. On the other hand, in vivo results showed that the highest antioxidant and anti-inflammatory effects were provided by the phytocomplexes in EG-PEVs, which favoured wound healing. Moreover, non-entrapped F. angustifolia extracts showed a marginal effect, comparable to that of free quercetin dispersion (control). In conclusion, our results depict that these extracts may find potential applications in biomedicin