Mechano-Chemical Synthesis, Structural Features and Optical Gap of Hybrid CH3NH3CdBr3 Perovskite

Hybrid methyl-ammonium (MA:CH3NH3+) lead halide MAPbX3 (X = halogen) perovskites exhibit an attractive optoelectronic performance that can be applied to the next generation of solar cells. To extend the field of interest of these hybrid materials, we describe the synthesis by a solvent-free ball-milling procedure, yielding a well crystallized, pure and moisture stable specimen of the Cd tribromide counterpart, MACdBr3, which contains chains of face-sharing CdBr6 octahedra in a framework defined in the Cmc21 (No 36) space group. The details of the structural arrangement at 295 K have been investigated by high angular resolution synchrotron x-ray diffraction (SXRD), including the orientation of the organic MA units, which are roughly aligned along the c direction, given the acentric nature of the space group. UV-vis spectra unveil a gap of 4.6 eV, which could be useful for ultraviolet detectors.

Solar-Blind Photodetector Based on NaTaO3/TiO2 Composite Film with Enhanced Photoelectric Performance

In this study, ultraviolet detectors based on NaTaO3/TiO2 were fabricated with enhanced detection performance towards solar-blind (200–280 nm) light. A TiO2 seed layer was introduced and served as a buffer layer between the fluorine tin oxide (FTO)-coated glass substrate and the TiO2 film, which increased the adhesion between them. The periodic stability and photoelectric characteristics of the detectors were studied and analyzed. The detectors showed a high performance when illuminated by 265 nm and 254 nm UV light. At −15 V bias, the dark current of the detector was only 70 pA. Under the bias of −15 V and the illumination of 254 nm, the maximum photo-to-dark current ratio reached 20, and the response time was less than 300 ms. Moreover, the detector exhibited a fast response time and remained very stable after numerous testing cycles. These results demonstrate the potential application of NaTaO3/TiO2 composites in UV detection.

Azobenzene-containing liquid crystalline composites for robust ultraviolet detectors based on conversion of illuminance-mechanical stress-electric signals

Wearable ultraviolet (UV) detectors have attracted considerable interest in the military and civilian realms. However, semiconductor-based UV detectors are easily interfered by elongation due to the elastic modulus incompatibility between rigid semiconductors and polymer matrix. Polymer detectors containing UV responsive moieties seriously suffer from slow response time. Herein, a UV illuminance–mechanical stress–electric signal conversion has been proposed based on well-defined ionic liquid (IL)-containing liquid crystalline polymer (ILCP) and highly elastic polyurethane (TPU) composite fabrics, to achieve a robust UV monitoring and shielding device with a fast response time of 5 s. Due to the electrostatic interactions and hydrogen bonds between ILs and LC networks, the ILCP-based device can effectively prevent the exudation of ILs and maintain stable performance upon stretching, bending, washing and 1000 testing cycles upon 365 nm UV irradiation. This work provides a generalizable approach toward the development of full polymer-based wearable electronics and soft robots.

Fast HILIC Method for Separation and Quantification of Non-Volatile Aromatic Compounds and Monosaccharides from Willow (Salix sp.) Bark Extract

Willow bark water extracts contain a mixture of chemically heterogeneous compounds. Fast screening techniques of the extracts are often needed to obtain information on the profile of bioactive and/or other valuable components in the extract. This is, however, a challenging task due to the different chemical structures of the components. Willow bark extract from the hybrid Karin contains several bioactive compounds such as aromatic picein, triandrin, and (+)-catechin. Willow bark extract also contains significant amounts of the monosaccharides fructose and glucose. Here, we demonstrate the applicability of hydrophilic interaction liquid chromatography, coupled with evaporative light scattering and ultraviolet detectors, for the simultaneous separation and quantification of major aromatic compounds and monosaccharides from the willow bark extract. The ternary eluent mixture consisting of acetonitrile, water, and methanol enabled the baseline separation of the main components in the extract in a short analysis time, which makes this method ideal for fast screening of the plant extracts and investigating the purity of fractionated bioactive compounds.

Azobenzene-Containing Liquid Crystalline Composites for Robust Ultraviolet Detectors Based on Conversion of Illuminance-Mechanical Stress-Electric Signals

Wearable ultraviolet (UV) detectors have attracted considerable interest in the military and civilian realms. However, semiconductor-based UV detectors are easily interfered by elongation due to the elastic modulus incompatibility between rigid semiconductors and polymer matrix. Polymer detectors containing UV responsive moieties seriously suffer from slow response time. Herein, a novel UV illuminance-mechanical stress-electric signal conversion has been proposed based on well-defined ionic liquid (IL)-containing liquid crystalline polymer (ILCP) and highly elastic polyurethane (TPU) composite fabrics, to achieve a robust UV monitoring and shielding device with a fast response time of 5 s. Due to the electrostatic interactions and hydrogen bonds between ILs and LC networks, the ILCP-based device can effectively prevent the exudation of ILs and maintain stable performance upon stretching, bending, washing and 1000 testing cycles upon 365 nm UV irradiation. This work provides a generalizable approach toward the development of full polymer-based wearable electronics and soft robots.

Photostability of CdTe Quantum Dots and Graphene Quantum Dots under their Continuous Visible and UV Irradiation

In the last decade, ultraviolet detectors have received significant attention due to their widespread use in civil and military fields. In this work, we have studied the effect of radiation of different ranges (UV and visible) on the spectral properties of CdTe quantum dots and wide-gap graphene QDs. The results obtained can be used to create an integrated UV radiation detector based on new physical principles