Spatially resolved nonlinear spectroscopy of colloidal semiconductor nanomaterials

• Grant number: 23/18267-5
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: June 01, 2024
• End date: May 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Lázaro Aurélio Padilha Junior
• Grantee: Carlos Henrique Domingues dos Santos
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Semiconductor nanoparticles are an important class of functional materials with potential for many applications, such as photovoltaic, light emission diodes, solar concentrators, biomarkers, lasing media, and single photon sources. Many studies reported in the literature discuss their linear and nonlinear optical properties depending on their composition, shape, size, crystalline structure, etc. However, all these properties are related to an ensemble in which heterogeneity of size, composition, and shape does not fundamentally reveal the property of a single nanoparticle. For this reason, some researchers have proposed single-particle spectroscopy (SPS) measurements to understand and explore the maximum efficiency of these materials. Unveiling the spectral dependence for optical properties is essential to materials tailored for applications in diverse areas. Therefore, this project aims to use a unique tunable-femtosecond single-particle-spectroscopy developed at the Ultrafast Spectroscopy Group to understand the linear and nonlinear optical properties of single nanoparticles (NCs) with different sizes, shapes, quantum confinement, and compositions of perovskite, chalcopyrite, and CdSe-based heterostructures besides, explore the behavior of these as gain media when deposited in microstructures. The first challenge of this project is to understand the spectral dependence of the nonlinear optical properties in the single particle regime, in particular, to determine the values of the two-photon absorption cross-section based on the photoluminescence saturation method. The second one is to study the laser activity of microcavities embedded with CdSe-based heterostructures and superparticles and, additionally, to explore whispering gallery modes (WGM) lasing from NCs-coated SiO2 or TiO2 microspheres.