Hang Mei,Zi-Yan Wang,Yue Zhai,Qiang-Qiang Zhu,Le Wang,Pei Liang
Vacancy-ordered double perovskites, the variant of metal-halide perovskites, have excellent potential for use in optoelectronic and thermoelectric devices. A narrow region of forming the stable vacancy-ordered double perovskite Cs2PdBr6 by the chemical potential calculation via the first principles method was reported. Perdew–Burke–Ernzerhof functionals were used to investigate the possible intrinsic defects and the corresponding formation energy of Cs2PdBr6. Under the Pd-rich condition, the VBr defect was spontaneously formed as it has the lowest formation energy among all donor defects. In contrast, the sample became a p-type conducting material with a high hole concentration under the Pd-poor condition. This indicates that the defect-induced decline of photoelectric properties of Cs2PdBr6 can be alleviated by regulating the VBr defect alone. Finally, the Cs2PdBr6 microcrystals were fabricated via hydrothermal synthesis. In addition, XRD, PL, and Raman spectroscopy were also performed on Cs2PdBr6 powder to characterize the microstructure and optical properties of the compound; the results showed that VBr defects can be formed spontaneously, which is consistent with our theoretical calculations.
Qiang Geng,Zhoujun He,Xun Chen,Wenxin Dai,Xuxu Wang
The photo-responded behavior of ZnO and its sensing response to ethylene or acetone under visible-light irradiation at room temperature were reported. A ZnO sensor without any response to target gas in the air atmosphere in dark at room temperature, exhibits not only a photo response but also an obvious sensing response to target gas in the air atmosphere under visible-light irradiation. It is suggested that the non-intrinsic photo-absorption induced by the native defects of ZnO (i.e., the two-photon or multi-photon excitation process via the intraband) may be responsible for the photo-responded behavior to the visible light . Moreover, a mechanism model that accounts for the solid-state process of photo-carrier generation/recombination is proposed to explain the photo-induced gas sensing response of ZnO under visible-light irradiation. This indicates that the photo-activated gas sensing response property of semi-conductor can be also caused by its non-intrinsic photo-absorption.
危险品化学品经营许可证（带存储）