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Cesium-containing triple cation perovskites are attracting significant attention as suitable tandem partners for silicon solar cells. The perovskite layer of a solar cell must strongly absorb the visible light and be transparent to the infrared light. Optical transmittance measurements of perovskite layers containing different cesium concentrations (0–15%) were carried out on purpose to evaluate the utility of the layers for the fabrication of monolithic perovskite/silicon tandem solar cells. The transmittance of the layers weakly depended on cesium concentration in the infrared spectral range, and it was more than 0.55 at 997 nm wavelength. It was found that perovskite solar cells containing 10% of cesium concentration show maximum power conversion efficiency.

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The design of a simple cost-effective planar semiconductor microwave diode is proposed. The operation is based on hot carrier phenomena and rectification of microwave currents flowing through the structure composed of two diodes connected in series and having different active region areas. A simplified technological process and the use of simplex semiconductor material result in the reduction of both the time and the cost of fabrication of a dual microwave diode. By choosing an appropriate GaAs substrate, two types of microwave diodes were produced simultaneously: one almost demonstrating the ohmic behaviour and the other two having the asymmetrical Schottky-like I-V characteristic. The Schottky-like planar diodes exhibited a higher responsivity to millimetre range microwave radiation and a faster response to pulsed (down to a nanosecond scale) excitation, but the ohmic ones demonstrated better noise properties.

The high efficiency of perovskite solar cells strongly depends on the quality of perovskite films and carrier extraction layers. Here, we present the results of an investigation of the photoelectric properties of solar cells based on perovskite films grown on compact and mesoporous titanium dioxide layers. Kinetics of charge carrier transport and their extraction in triple-cation perovskite solar cells were studied by using transient photovoltage and time-resolved photoluminescence decay measurements. X-ray diffraction analysis revealed that the crystallinity of the perovskite films grown on mesoporous titanium dioxide is better compared to the films grown on compact TiO2. Mesoporous structured perovskite solar cells are found to have higher power conversion efficiency mainly due to enlarged perovskite/mesoporous -TiO2 interfacial area and better crystallinity of their perovskite films.