Synthesis of ultrasmall quantum dots by redirecting kinetics-based crystal growth to thermodynamics-based crystal dissolution

Abstract

Ultrasmall quantum dots (< 2 nm) have been synthesised by redirecting crystal growth to dissolution during the synthetic process. The redirection is carried out with a controlled quenching–isothermal annealing process, where quantum dots are first grown and then quenched to a lower temperature, followed by thermodynamically reducing the size in an isothermal annealing process. The synthesised ultrasmall quantum dots are of high quality and their photoluminescence efficiency is generally more than 60%. With polymer overcoating, the blue-emitting ultrasmall quantum dots are water dispersible and stable for more than nine months.