Highly Emissive Zero-Dimensional Cesium Lead Iodide Perovskite Nanocrystals with Thermally Activated Delayed Photoluminescence

J Phys Chem Lett. 2023 Mar 30;14(12):2933-2939. doi: 10.1021/acs.jpclett.3c00219. Epub 2023 Mar 17.

Abstract

We utilized a modified reverse-microemulsion method to develop highly emissive and photostable zero-dimensional (0D) Cs4Pb(Br1-xIx)6 perovskite nanocrystals (PNCs). We employed single-particle photoluminescence (PL) spectroscopy to explore blinking statistics and demonstrate single-photon emission from individual PNCs. Low-temperature blinking and photon correlation studies revealed a transition from single- to multiphoton emission with progressively longer "delayed" PL components, reaching ∼70 ns at room temperature and representing a distinctive behavior to previously known iodide PNCs. Such thermally activated PL emission is explained by the existence of defect-related "reservoir" states, feeding back into the PNC's emissive state and providing multiple photons within a single excitation cycle. This work establishes a new member in the 0D class of perovskite materials, studies its photophysical properties, and reveals its potential for future optoelectronic applications.