The electron transport layer (ETL) is critical to carrier extraction for perovskite solar cells (PSCs). Moreover, the morphology and surface condition of the ETL could influence the topography of the perovskite layer. ZnO, TiO₂, and SnO₂ were widely investigated as ETL materials. However, TiO₂ requires a sintering process under high temperature and ZnO has the trouble of chemical instability. SnO₂ possesses the advantages of low-temperature fabrication and high conductivity, which is critical to the performance of PSCs prepared under low temperature. Here, we optimized the morphology and property of SnO₂ by modulating the concentration of a SnO₂ colloidal dispersion solution. When adjusting the concentration of SnO₂ colloidal dispersion solution to 5 wt.% (in water), SnO₂ film indicated better performance and the perovskite film has a large grain size and smooth surface. Based on high efficiency (16.82%), the device keeps a low hysteresis index (0.23).

With the development of the semiconductor industry, research on photoelectronic devices has been emphasized. In this paper, a molecular semiconductor material with a narrow bandgap of hexane-1,6-diammonium pentaiodobismuth (HDA-BiI₅) was utilized to prepare photodetectors without electron transport layers. Using a single light source, the effects of different wavelengths and different powers on the photoresponsivity, switching ratio, specific detectivity, and external quantum efficiency of the device were investigated. It is demonstrated that this device has excellent responsivity, specific detectivity, stability, and repeatability, and this work will help expand the application of molecular semiconductor materials for photodetection.

Photoelectric devices can be so widely used in various detection industries that people began to focus on its research. The research of photoelectric sensors with high performance has become an industry goal. In this paper, we prepared photodetectors using organic–inorganic hybrid semiconductor materials with narrow bandgap hexane-1,6-diammonium pentaiodobismuth (HDA-BiI₅) and investigated the detector photoresponse and time-response characteristics under a single light source. The device exhibits high photoresponsivity and fast response time. The photoresponsivity can reach 1.45 × 10⁻³ A/W and 8.5 × 10⁻⁴ A/W under laser irradiation at 375 nm and 532 nm wavelengths, and the rise and decay times are 63 ms and 62 ms, 62 ms and 64 ms, respectively. The device has excellent performance and this work can extend the application of organic–inorganic hybrid semiconductor materials in photovoltaic and photodetectors.

A quadrature fiber optic Fabry–Perot cavity microphone based on a differential cross multiplication algorithm consists of a pair of fibers and a membrane. It has many advantages such as high sensitivity, a simple structure, and resistance to electromagnetic interference. However, there are no systematic studies on its key performance, for example, its frequency response and dynamic range. In this paper, a comprehensive study of these two key parameters is carried out using simulation analysis and experimental verification. The upper limit of the frequency response range and the upper limit of the dynamic range influence each other, and they are both affected by the data sampling rate. At a certain data sampling rate, the higher the upper limit of the frequency response range is the lower the upper limit of the dynamic range. The quantitative relationship between them is revealed. In addition, these two key parameters also are affected by the quadrature phase deviation. The quadrature phase deviation should not exceed 0.25π under the condition that the demodulated signal intensity is not attenuated by more than 3 dB. Subsequently, a short-step quadrature Fabry–Perot cavity method is proposed, which can suppress the quadrature phase deviation of the quadrature fiber optic Fabry–Perot cavity microphone based on the differential cross multiplication algorithm.

The depolarization field of ferroelectric photovoltaic materials can enhance the separation and transport of photogenerated carriers, which will improve the performance of photovoltaic devices, thus attracting the attention of researchers. In this paper, a narrow bandgap molecular ferroelectric Hexane-1,6-diammonium pentaiodobismuth (HDA-BiI₅) was selected as the photo absorption layer for the fabrication of solar cells. After optimizing the ferroelectric thin film by the antisolvent process, the effect of different polarization voltages on the performance of ferroelectric devices was studied. The results showed that there was a significant increase in short-circuit current density, and the photoelectric conversion efficiency showed an overall increasing trend. Finally, we analyzed the internal mechanism of the effect of polarization on the device.