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Perovskite halide materials are currently attracting considerable attention owing to their superior optical and electrical properties. This study proposes a reliable process for synthesizing hybrid nanomaterials made of methylammonium tin iodide (MASnI3) submicron spheres and tin dioxide (SnO2) nanowires. Post-fabricated hybrid nanomaterials were investigated for NO2 sensing properties at 25 °C in the dark. The effect of moisture on the NO2 sensitivity of this material was investigated. The durability of sensor components using this material was also investigated. In this paper, we also discuss the NO2 sensitivity mechanism of MASnI3/SnO2 hybrid nanomaterials in detail.

Biaxial p-SnO/n-ZnO heterostructured nanowires (average length of 10 μm) were grown onto a glass substrate by thermal evaporation in vacuum. These nanowires had spherical ball tips, and the size of the SnO part increased gradually from the top to the bottom of the nanowire, but the corresponding size of ZnO varied slightly. The Sn-Zn alloy formed in the tips resulted in determined as the catalyst of the growth of the ZnO nanowires. The growth process of the p-SnO/n-ZnO biaxial nanowires is discussed based on vapor-liquid-solid (VLS) based on the subsequent growth process: the VLS catalytic growth of the ZnO nanowire and subsequent epitaxial SnO growth on the sidewall of the pregrown ZnO nanowire. An epitaxial relationship, (001)SnO//(110)ZnO and [110]SnO//[002]ZnO, was observed in the biaxial p-SnO/n-ZnO heterostructured nanowires. The gas-sensing properties of the as-synthesized p-SnO/n-ZnO nanowires were investigated. The results show that the device exhibit a good performance to the ppb-level NO2 at room temperature (25 °C) without light illumination. The detection limit of the p-SnO/n-ZnO sensor to NO2 is 50 ppb. Moreover, the NO2-sensing properties of the p-SnO/n-ZnO device were investigated under various relative humidity. Finally, the NO2-sensing mechanism of the p-SnO/n-ZnO nanowires was proposed and discussed.

Herein we report on the growth of layered BiI 3 nanoplates materials and their sensing properties of NO 2 under violet light illumination. The BiI 3 nanoplates were grown on a glass substrate using a chemical vapor deposition (CVD) system, with an average thickness of 30 nm and the lateral dimension of 150–170 nm. Their photo-induced sensing response for 20 ppm NO 2 and the response/recovery time are approximately ~11.2% and 18/36 s, respectively. The limit of detection (LOD) of NO 2 for the BiI 3 sensor is 25 ppb. A possible light-induced gas-sensing mechanism was proposed and investigated for the BiI 3 nanoplate.

In this study, Cs2SnI6 thin film was synthesized on a glass substrate through a two-step process using the chemical vapor deposition (CVD) method and was subsequently used as a NO2 gas sensor. First, the CsI spheres with an average diameter of 360 nm were fabricated on the glass substrate using a CVD system at 240 °C. Second, Cs2SnI6 film was formed through the reaction of CsI spheres with SnI4 vapor at 200 °C for 1 h. Finally, the as-synthesized Cs2SnI6 thin film based gas sensor was then fabricated to explore its potential applications. The results indicated that the device showed good selectivity, stability, and detection for NO2 with low concentration at room temperature. In addition, the effect of humidity on NO2-sensing performance of the device was further studied. Furthermore, the NO2 sensing mechanism of the Cs2SnI6 thin film was discussed. Hence, this study helps understand the gas sensing mechanism of halide perovskite Cs2SnI6 and the room temperature development of NO2 gas sensors.

In this study, a thin film of Cs2TeI6 perovskite with a thickness of 1.27 mm was prepared on a glass substrate via a non-solution process. The characteristics of the material such as phase structure, morphology, optical absorption were studied. The gas-sensing properties of the Cs2TeI6-based sensor were investigated at 25 °C using various gases under illumination of a 450-nm laser. Under the blue-light illumination, the sensor exhibited good selectivity toward NO2 gas, with a very low limit of detection of 25 ppb and responsivity of 4.4% toward 1 ppm NO2. The NO2-sensing mechanism was proposed and discussed in term of a surface depletion model. The effects of light intensity, light wavelength, humidity, and long-term duration on NO2-sensing performances were further studied, showing its potential for application into NO2 gas sensors at room temperature.

Biaxial p-SnO/n-ZnO heterostructured nanowires (average length of 10 μm) were grown onto a glass substrate by thermal evaporation in vacuum. These nanowires had spherical ball tips, and the size of the SnO part increased gradually from the top to the bottom of the nanowire, but the corresponding size of ZnO varied slightly. The Sn-Zn alloy formed in the tips resulted in determined as the catalyst of the growth of the ZnO nanowires. The growth process of the p-SnO/n-ZnO biaxial nanowires is discussed based on vapor-liquid-solid (VLS) based on the subsequent growth process: the VLS catalytic growth of the ZnO nanowire and subsequent epitaxial SnO growth on the sidewall of the pregrown ZnO nanowire. An epitaxial relationship, (001)

Perovskite halide materials are currently attracting considerable attention owing to their superior optical and electrical properties. This study proposes a reliable process for synthesizing hybrid nanomaterials made of methylammonium tin iodide (MASnI3) submicron spheres and tin dioxide (SnO2) nanowires. Post-fabricated hybrid nanomaterials were investigated for NO2 sensing properties at 25°C in the dark. The effect of moisture on the NO2 sensitivity of this material was investigated. The durability of sensor components using this material was also investigated. In this paper, we also discuss the NO2 sensitivity mechanism of MASnI3/SnO2 hybrid nanomaterials in detail.

Cs2SnI6 is an all-inorganic, air-stable and Pb-free halide perovskite material. In this work, we propose a low-pressure chemical vapor deposition method that enables the synthesis of continuous Cs2SnI6 thin films. Some technical parameters such as the deposition time and the deposition temperature of CsI were varied to investigate the morphology and thickness of Cs2SnI6 thin films. The film was further undergone an annealing treatment in SnI4 ambient to enhance characteristics, such as the long-term stability and the structural, optical and electrical properties. After annealing in SnI4, the film was found to be stable in ambient air (40–60% humidity) for 30 days. The film shows n-type semiconducting with an energy bandgap of 1.58 eV. Its absorption coefficient is higher than 3.4 × 104 cm−1 in the visible region with a maximum value of 0.9 × 105 cm−1 at the wavelength of 420 nm. The carrier concentration increased to 5.5 × 1017 cm−3, and the resistivity declined to 3.1 Ω.cm.

Operation of ZnO/In2S3/Cu2Sn3S7/Mo solar cell was calculated using the SCAPS software. Main input data were energy band gap Eg, absorption coefficient α, thickness d, mobility μ and carrier concentration n of the ZnO, In2S3 and Cu2Sn3S7 films obtained from experiments. In all calculation processes, parameters of the ZnO (Eg = 3.3 eV, d = 0.2 μm, μn = 100 cm2/(Vs)) and In2S3 (Eg = 2.96 eV, d = 0.1 μm, μn = 50 cm2/(Vs)) films were kept constant. Effects of thickness d and carrier concentration np of the Cu2Sn3S7 (αmax = 4.2×104 cm-1, Eg = 1.46 eV) film on Voc, Jsc, Vm, Jm, FF and η of the cell were investigated in the ranges of d = 0.3 – 3.5 μm and np = 1017 – 1020 cm-3. Under the standard AM 1.5G illumination at 300 K, the ZnO/In2S3/Cu2Sn3S7/Mo solar cell having Rs = 10 Ω.cm2 and Rsh = 1×106 Ω.cm2 using Cu2Sn3S7 film having d = 2 μm, αmax = 4.2×104 cm-1, Eg = 1.46 eV, μp = 15 cm2/(Vs) and np = 1020 cm-3 has the highest conversion efficiency ηmax = 18.0 % with Voc = 0.98 V, Jsc = 31.2 mA/cm2, Vm = 0.62 V, Jm = 28.8 mA/cm2 and FF = 58.8 %.

We investigate the edge effects of the optical analogue of the quantum relativistic Dirac solitons in binary waveguide arrays with Kerr nonlinearity when one tail of the Dirac soliton is truncated. We show that if the outermost waveguide of the binary waveguide array hosts the intense component of the truncated Dirac soliton, then Dirac soliton will be repeatedly bent towards the binary waveguide array edge. In the contrast, if the outermost waveguide of the binary waveguide array hosts the weak component of the truncated Dirac soliton, then Dirac soliton will be pushed away from the binary waveguide array edge. To the best of our knowledge, these unique features have not been found in any other systems.