Search

Manipulating the propagation of photons is meaningful for optical data recognition but extremely challenging. Recently, the metal halide perovskite semiconductors present great potential in photoni...

Si nanoparticle features multiple excellent properties, such as high theoretical capacity of 4200 mAh/g and low volume expansion effect, and it is regarded as an outstanding anode electrode material for Li-ion batteries. In this study, we obtained Si nanoparticles through pulsed discharge of Si strips and analyzed the pulsed discharge process based on recorded current data. The recovered samples were characterized by various techniques, such as XRD, Raman spectroscopy, SEM, and TEM. The characterization results confirm that the recovered samples are smooth spherical Si nanoparticles smaller than 200 nm. Our investigation reveals that the charging voltage is a key factor to adjust the size distribution of recovered Si nanoparticles. In the charging voltage range of 4–7 kV, the increase of charging voltage value decreases D90 (the particle size at the 90% undersize point in the size distribution) of recovered Si nanoparticles from 48.7 to 24.9 nm. In the charging voltage range of 7–12 kV, the increase of charging voltage value increases D90 of recovered Si nanoparticles from 24.9 to 66.5 nm. Thus, the critical charging voltage value is 7 kV, at which condition D90 of formed Si nanoparticles is the minimum (24.9 nm). In addition, the analysis of discharge current curves indicates three discharge stages, including semiconductor joule heating, conductor joule heating, and plasma discharge, which possess correlation to the size distribution of formed Si nanoparticles.

The carrier diffusion length (LD) is of great relevance to the quantum efficiencies of organic-inorganic perovskites. However, so far there is no direct and noncontact measurement of the carrier diffusion length in this emerging material. Herein, we directly visualize the carrier diffusion length of organic-inorganic perovskites via spatial mapping of photoluminescence. Our results reveal that the carrier diffusion length (LD) is 6.25 μm for three-dimensional FAPbBr3 single crystals. Further, we discover that nonlinear and nonradiative effects can be neglectable during the diffusion process of photogenerated carriers in FAPbBr3 single crystals. In contrast, two-dimensional BA2PbI4 single crystals display shorter LD (2.40 μm) due to the transport barrier from their insulating organic layer. Our work simplifies the complicated operation for carrier diffusion length measurements, which is fundamentally important for technical development and scientific research on organic-inorganic perovskites.