Continous Injection Synthesis of Large Perovskite Nanocrystals for Bright and Fast Emission at Low Temperature

Weakly-confined cesium lead halide perovskite nanocrystals (PNCs) boast bright and fast single photon emission at low temperature, making them promising quantum light sources. In this size regime, where the edge length of the crystal is larger than the Bohr exciton diameter, the excited state lifetime is inversely related to the crystal volume. Consequentially, increasing the nanocrystal size can accelerate the radiative rate, allowing the emission to further approach the transform limit necessary for quantum information science applications. However, the realization of large, high-quality nanocrystals has been hindered by colloidal and temperature instability as well as phase transformations.
In this work, we developed a continuous injection growth procedure to prepare nanocrystals with a 200-fold volume increase over current literature standards while maintaining colloidal stability and curtailing trap states. Transmission electron microscopy images reveal uniform, cuboidal nanocrystals with size distributions less than 10% in deviation, while ensemble measurements show bright emission of over 70% quantum yield. Optical spectroscopy of single nanocrystals at cryogenic temperatures reveals stable emission and fast radiative rates that accelerate with increasing edge lengths. Our novel synthetic technique establishes a new avenue for perovskite nanocrystal synthesis and demonstrates the rational design and preparation of PNCs with enhanced quantum emission properties.