Synthesis and single-particle photophysics of BaZrS₃ chalcogenide perovskite quantum dots

There has been growing interest in replacing halide perovskite materials because of their toxicity and poor stability, and chalcogenide perovskites have emerged as strong candidates for such substitution. We synthesize colloidal BaZrS₃ quantum dots (QDs) by a hot injection method and study their photophysical properties on the level of single particles. The as-synthesized QDs exhibit the BaZrS₃ crystal structure and a broad size distribution from 2 nm to 18 nm, with an average size of 7.6 nm. Individual QDs emit photoluminescence (PL) with intensities that fluctuate over time, displaying the characteristic PL intermittency (blinking). Simultaneous monitoring of single QD PL lifetime and intensity reveals a B-type blinking mechanism involving population of a surface trap state. Passivating these traps by ligand engineering results in a substantial increase in PL intensity. Single QD PL spectra show narrow linewidths (with average FWHM of 25.6 nm) and their peak positions span a wide range from 468 to 646 nm. This experimentally observed distribution matches well with the theoretical range calculated from the measured QD size distribution, confirming that the PL emission is governed by quantum confinement. The broad size tunability of the bandgap, combined with the narrow spectral linewidth, highlights the potential of BaZrS₃ QDs for next-generation light-emitting optoelectronic devices.