Outstanding nonlinear optical properties of methylammonium- and Cs-PbX3 (X = Br, I, and Br–I) perovskites: Polycrystalline thin films and nanoparticles

Metal Halide Perovskites (MHPs) have arisen as promising materials to construct cost-effective photovoltaic and light emission devices. The study of nonlinear optical properties of MHPs is necessary to get similar success in nonlinear photonic devices, which is practically absent in the literature. The determination of the third order nonlinear coefficients is typically done by the Z-scan technique, which is limited by the scattering of polycrystalline thin films. In this work, we have studied nonlinear optical properties of polycrystalline CH3NH3PbX3 (MAPbX3) thin films and colloidal CsPbX3 nanoparticles with three different bandgaps (X3 = I3, Br3, and Br1.5I1.5). Their bright generation o…

Enhanced nanoscopy of individual CsPbBr3 perovskite nanocrystals using dielectric sub-micrometric antennas

We demonstrate an efficient, simple, and low-cost approach for enhanced nanoscopy in individual green emitting perovskite (CsPbBr3) nanocrystals via TiO2 dielectric nanoantenna. The observed three- to five-fold emission enhancement is attributed to near-field effects and emission steering promoted by the coupling between the perovskite nanocrystals and the dielectric sub-micrometric antennas. The dark-field scattering configuration is then exploited for surface-enhanced absorption measurements, showing a large increase in detection sensitivity, leading to the detection of individual nanocrystals. Due to the broadband spectral response of the Mie sub-micrometric antennas, the method can be e…

One-step formation of nanostructures on silicon surfaces using pure hydrogen-radical-initiated reactions

One-step formation of silicon nanowires, sheets, and texture surface on a silicon substrate has been achieved using hydrogen-radical etching reactions. Metallic tungsten and for comparison purposes a tungsten hot wire, were used as catalysts for the hydrogen-molecular cracking. It was shown that a variety of surface structures on silicon such as inverted pyramid texture, V-groove texture, dense silicon nanowire growth over texture, and nanosheet structure can be obtained by controlling the process conditions. The obtained results suggested that the formation of nanotungsten silicide particle is an essential prerequisite to obtain these structures. The particles work as an etching mask again…

Scientific and Technical Contributions from Research Projects

The main goal of this project is to demonstrate the advantages of sensor integration on a remotely controlled robotic platform for increasing operator safety and improving the classification of explosive targets. This is accomplished by combining the imaging provided by radars and an optoelectronic sensor, a time-of-flight (ToF) depth camera. An additional aim is to demonstrate the operability and practicality of the system in a field with landmine simulants having plastic cases.

Spray-driven Solid-State Halide Exchange in CsPbX3 Nanocrystal Films