No abstract

No abstract

Unlike organic-inorganic hybrid perovskites, all-inorganic cesium lead halide perovskites hold great promise for developing high-performance optoelectronic devices, owing to their improved stability. Herein, we investigate the perovskite-related CsPb 2 Br 5 nanoplatelets (NPLs) with tunable emission wavelengths via changing the reaction temperatures to 100°C, 120°C, and 140°C. Reaction temperature plays a key role in determining the shapes and thicknesses of the resulting CsPb 2 Br 5 NPLs. A higher temperature is in favor of the formation of smaller and thicker NPLs. To develop their potential applications in optoelectronic devices, green light emitting diodes (LEDs) and photodetectors based on CsPb 2 Br 5 NPLs are fabricated. The green LEDs based on CsPb 2 Br 5 NPLs synthesized at 140°C exhibit an excellent pure green emission (full width at half-maximum of <20 nm) and display a luminous efficiency of 34.49 lm∕W under an operation current of 10 mA. Moreover, the photodetector based on CsPb 2 Br 5 NPLs synthesized at 100°C has better performance with a rise time of 0.426 s, a decay time of 0.422 s, and a ratio of the current (with and without irradiation) of 364%.

All-inorganic perovskite CsPbBr₃ quantum dots (QDs) with an emission peak of around 520 nm were synthesized by a hot-injection method, and were systematically studied as green phosphor for light-emitting diodes (LEDs). Highly pure green light with an emission peak of 534 nm and a full-width at half-maximum (FWHM) about 20 nm was achieved using CsPbBr₃ QDs and GaN LEDs. Commission Internationale Ed I'Eclairage coordinate of the fabricated green LEDs was (0.203, 0.757). Compared to GaN LEDs, the current-voltage characteristic of the green LED did not show any degradation. Moreover, the green LEDs displayed a luminous efficiency of 31.92 lm/W under an injection current of 10 mA.

This paper investigates the Frequency Modulation Continuous Wave (FMCW) radar sensor for multi-target displacement measurement in Structural Health Monitoring (SHM). The principle of three-dimensional (3-D) displacement measurement of civil infrastructures is analyzed. The requirements of high-accuracy displacement and multi-target identification for the measuring sensors are discussed. The fundamental measuring principle of FMCW radar is presented with rigorous mathematical formulas, and further the multiple-target displacement measurement is analyzed and simulated. In addition, a FMCW radar prototype is designed and fabricated based on an off-the-shelf radar frontend and data acquisition (DAQ) card, and the displacement error induced by phase asynchronism is analyzed. The conducted outdoor experiments verify the feasibility of this sensing method applied to multi-target displacement measurement, and experimental results show that three targets located at different distances can be distinguished simultaneously with millimeter level accuracy.

No abstract

No abstract

No abstract