Absorption properties of boron nitride quantum dots: effects of solvents

Boron nitride quantum dots combine several unique properties, including chemical stability, biocompatibility, and low cytotoxicity. These properties and tunable optical characteristics make them promising for use in boron neutron capture therapy simultaneously as therapeutic agents and fluorescent markers for cancer cells. In this paper we present a case study, in which the electronic structure of these dots is analyzed using DFT and TD-DFT methods providing a deeper understanding of their absorption properties. Our approach enables an assessment of the overall effect of solvents on the absorption properties of these dots obtained by the solvothermal method. We show that solvents, being the medium for the synthesis of quantum dots, actively participate in the formation of their absorption properties. It is demonstrated theoretically and experimentally that the change in optical properties is caused by the direct attachment of solvent molecules to the quantum dot surface. We find that there is a fundamental absorption edge at a value of 215-220 nm for quantum dots with a diameter of 10-15 nm.