Low-phonon nanocrystals doped with lanthanide ions – new materials for efficient up-conversion and photon avalanche
Principal investigator: PhD Małgorzata Misiak
Lanthanide-doped nanoparticles are optically active materials capable of converting photons (quanta of light) and emitting radiation either at lower energy (Stokes emission) or higher energy (anti-Stokes emission). Such nanoparticles can be applied in a variety of areas, including bioimaging, photodynamic therapy, and super-resolution imaging.
The spectroscopic properties of lanthanide ions depend strongly on the host matrix in which they are embedded, particularly on the lattice vibrations, known as phonons. High-phonon-energy matrices lead to quenching of lanthanide luminescence via multiphonon relaxation, and the probability of these processes increases with phonon energy. For this reason, research into low-phonon-energy matrices is essential for designing nanomaterials capable of emission from higher energy levels (i.e., at different wavelengths and colors). Among low-phonon materials, lanthanide chlorides and bromides are particularly interesting.
Unfortunately, lanthanide chloride nanocrystals are hygroscopic and degrade upon exposure to water or humid environments. Therefore, the project will focus on more water-resistant matrices such as perovskites CsPbX3 and KPb2X5, where X represents chlorine or bromine. The aim of the project is to develop methods for synthesizing lanthanide-doped CsPbX3 and KPb2X5 materials at the nanoscale, as well as methods for obtaining core–shell structures.
Another goal is to functionalize the surface of the synthesized materials to make them water-resistant and suitable for use in aqueous colloidal suspensions. The project will also investigate the usefulness of the resulting materials in terms of Stokes and anti-Stokes emission, including photon avalanche emission, and will explore their optical properties for contactless luminescence thermometry.
The project will additionally expand knowledge of the spectroscopic properties of selected low-phonon lanthanide-doped nanomaterials, as well as their surface functionalization and engineering, enabling applications across fields ranging from photonics to biology and medicine. Moreover, studying the temperature-dependent optical properties of the proposed nanomaterials will expand the library of available materials suitable for highly sensitive, contactless luminescent thermometry.