Low-Temperature Vapor-Phase Anion-Exchange Strategy for Wide-Bandgap Double-Perovskite Cs2AgBiCl6 Films toward Weak Ultraviolet Light Imaging.

Low-temperature synthesis of high-quality, high-stability, wide-bandgap perovskite films by solution methods is still challenging. Herein, large-scale wide-bandgap Cs2AgBiCl6 (CABC) double perovskite films are synthesized by a vapor-phase anion-exchange strategy. By dedicatedly designing an ultrathin TiO2 modification layer between the substrate and double perovskites, high-quality heterojunctions with matched energy band alignment are formed, contributing to a remarkably enhanced ON/OFF ratio of 2.4 × 104 (86 times) and a responsivity of 16 mA W-1 (12 times). Additionally, the ultraviolet photodetectors (UV PDs) exhibit an excellent UV detection limit of 1.18 µW cm-2 (20 nW), a broad linear dynamic range of 146 dB, and a high specific detectivity of 2.06 × 1011 Jones, as well as long-term stability. Finally, we further demonstrate a weak UV imaging system using CABC UV PDs as imaging sensors. The system is capable of imaging weak UV signals as low as 2.94 µW cm-2 (50 nW). Our results provide a feasible approach for low-temperature fabrication of wide-bandgap perovskite UV PDs and explore the promising application for weak UV detection and imaging.

Thermal-behavior study of chlorine released from composite refuse derived fuel.

In order to reduce secondary pollution during the incineration of composite refuse derived fuel (CRDF), the combustion features and the emission behavior of chlorine in CRDF containing coal were analyzed. The former was analyzed using thermo-gravimetric and the latter by gas chromatography-mass spectrometry. The release rate of inorganic chlorine during combustion reached 90 mass% at temperature between 773.15 and 873.15K. On the other hand, approximately 84 mass% release rates was resulting from pyrolysis at 723.15K. When temperature reached above 1073.15K, it was noticed that higher concentration of organic chlorine in different organic compounds were produced in the processing of pyrolysis compared with those released from the combustion processing. From the thermo-gravimetric analysis using a self-designed system, three distinct phases were detected in the thermal process of CRDF. The first phase occurred at temperature between 473 and 573K and its mass loss was about 38.50%. The second phase between temperature regions of 673-773K with a mass loss of 20.35%. The third phase was observed at the temperature between 873 and 1073K with 22.25% mass loss.