The Effects of Temperature on the Growth of a Lead-Free Perovskite-Like (CH3NH3)3Sb2Br9 Single Crystal for An MSM Photodetector Application

We have fabricated a photodetector based on (CH3NH3)3Sb2Br9 (MA3Sb2Br9) lead-free perovskite-like single crystal, which plays an important role in the optoelectronic characteristics of the photodetector as a perovskite-like photosensitive layer. Here, MA3Sb2Br9 single crystals were synthesized by an inverse temperature crystallization process with a precursor solution at three different growth temperatures, 60 °C, 80 °C, and 100 °C. As a result, a MA3Sb2Br9 single crystal with an optimum growth temperature of 60 °C presented a low trap density of 2.63 × 1011 cm−3, a high charge carrier mobility of 0.75 cm2 V−1 s−1, and excellent crystal structure and optical absorption properties. This MA3Sb2Br9 perovskite-like photodetector displayed a low dark current of 8.09 × 10−9 A, high responsivity of 0.113 A W−1, and high detectivity of 4.32 × 1011 Jones.

Influence of Ag@SiO2 with Different Shell Thickness on Photoelectric Properties of Hole-Conductor-Free Perovskite Solar Cells

In this paper, Ag@SiO2 core-shell nanoparticles (NPs) with different shell thicknesses were prepared experimentally and introduced into the photosensitive layer of mesoscopic hole-conductor-free perovskite solar cells (PSCs) based on carbon counter electrodes. By combining simulation and experiments, the influences of different shell thickness Ag@SiO2 core-shell nanoparticles on the photoelectric properties of the PSCs were studied. The results show that, when the shell thickness of 0.1 wt% Ag@SiO2 core-shell nanoparticles is 5 nm, power conversion efficiency is improved from 13.13% to 15.25%, achieving a 16% enhancement. Through the measurement of the relevant parameters of the obtained perovskite film, we found that this gain not only comes from the increase in current density that scholars generally think, but also comes from the improvement of the film quality. Like current gain, this gain is related to the different shell thickness of Ag@SiO2 core-shell nanoparticles. Our research provides a new direction for studying the influence mechanism of Ag@SiO2 core-shell nanoparticles in perovskite solar cells.

Kinetics of photorestoration of copper(II) in compositions on the basis of acetate of copper and the tetraftorpropianat of copper

In the technology of manufacturing printed circuit boards by additive method, photoselective activation of dielectric materials is widely used. In order to obtain a given circuit pattern on the surface and in the holes of the printed circuit board it is necessary to form catalytically active centers for further chemical metallization. The aim of the work was to study the physical and chemical patterns of the photoactivation process of dielectric materials. Copper acetate (CuAc2) and copper tetrafluoropropyanate (Cu(TFP)2) having sufficiently high spectral sensitivity to UV radiation and good solubility in water were added to the analysed photosensitive compositions as copper-containing compounds (photopromotors). Chemical sensitizer in analysed photosensitive compositions is water-soluble organic compound – disodium salt of anthraquinone-2,6-disulfonic acid (Na2AS), acting as optical sensitizer in processes of photochemical reduction of copper(II). The process of photochemical reduction of copper(II) in the presence of sensitizers is possible with the presence of secondary reducing agents – alcohols. Such compounds are sorbitol and ethyl alcohol. In comparison with solutions, the study of the process of photo recovery of copper(II) in the dry layer of the photoactivator under the influence of ultraviolet radiation requires a special approach. A quantitative evaluation of the photochemical process was chosen to pass the photosensitive layer. On the transmission spectra of the photosensitive layer, it is clearly possible to distinguish a maximum at a wavelength of 520 nm, from the change of which during ultraviolet irradiation it is possible to judge the progress of photochemical transformation in the dry layer of photocomposition. The kinetics of the photochemical process were monitored by the transmission spectra of the 520 nm samples, which were taken immediately after irradiation. Survey of spectra was carried out on spectrophotometer of grade СF-18 in visible region of spectrum relative to chromatographic paper FN-5 without photoactivator. Mercury-quartz lamp of DRT-1000 grade was used as radiation source. Exhibiting carried out on GG-2258 installation in a special vacuum frame at distance 40 cm from a radiation source A phenomenological description is given of the process of photo-recovery of copper(II) in solid phase in compositions based on copper acetate and copper tetrafluoropropionate in form of kinetic equations. Fractional partial reaction orders by components of the photocomposition indicate the complexity of the process in the systems studied. It has been found that, depending on the kind of copper-containing compound, the process of copper photo-recovery is described by different kinetic equations, suggesting a different mechanism of copper(II) photo-recovery. It has been shown that complicating the composition of the photosensitive composition results in a slight change in the reaction order of the main components. The description of the kinetics of the photochemical process by means of mathematical equations will allow to determine in advance the time by which the specified degree of conversion of the substance will be achieved.

Efficient photodiode-type photodetectors with perovskite thin films derived from an MAPbI3 single-crystal precursor

This research exhibits an efficient photodetector based on a perovskite photosensitive layer derived from an MAPbI3 single-crystal precursor.

ZnO Nanosheets Exhibiting High UV Blocking Efficiency for Effective Application in Sunscreen

Zinc oxide (ZnO) nanopowder has been prepared by wet chemical method and tested for its effective UV blocking property coated on photosensitive paper/fabric samples. Zinc acetate dihydrate and ammonium hydroxide were adopted as synthesis precursors. Phase and crystallographic analysis of the samples have been carried out by X-ray diffraction (XRD) and show that ZnO sample belong to hexagonal wurtzite phase without any impurity. Surface morphology of ZnO samples studied by field emission scanning electron microscopy (FESEM) shows the formation of nanosheets with porous structure. These porous nanosheets have surface area varying from 5000-30000 nm2 with thickness 10-15 nm. ZnO nanosheets on the photosensitive paper show UV absorbance around 300 nm as observed from the absorption spectrum. The reflectance spectrum of ZnO also shows its effectiveness in reflecting UV light in the region of 350-400 nm. The sun protection factors (SPF) and ultraviolet protection factors (UPF) calculated from the above studies are also encouraging implicating the use of ZnO in sunscreen. The above experiment is carried out by preparing a photosensitive layer similar to human skin. Similar experiment has also been carried out by treating ZnO nanosheets on fabric samples and studying its effectiveness for protection from UV rays.