Tuning Blinking Behavior of Highly Luminescent Cesium Lead Halide Nanocrystals through Varying Halide Composition

Colloidal cesium lead halide nanocrystals (CsPbX₃, where X = Cl, Br, and I) are newcomer optoelectronic materials and have been successfully utilized as bright light sources and high-efficiency photovoltaics due to their facial solution processability. However, detailed understanding of their fundamental chemistry and photophysics behavior are urgently required for utilizing the full potential of the perovskite nanocrystals. In this work, we described a simple and efficient approach for regulating the blinking behavior of the CsPbX₃ nanocrystals through varying halide composition. We systematically investigated the ensemble and single-particle optical properties of the mixed-halide CsPbBr_<i>x</i>I_3–<i>x</i> and CsPbBr_3–<i>y</i>I_<i>y</i> nanocrystals via two different anion-exchange routes (Br^– ions → I^– ions and I^– ions → Br^– ions). The power-law fitting results demonstrated that both the “on” and “off” events of their fluorescence exhibited a similar power-law rule to those of the cadmium chalcogenide nanocrystals (e.g., CdSe nanocrystals). Under optimum conditions, the percentage of “non-blinking” CsPbBr_3–<i>y</i>I_<i>y</i> nanocrystals (the “on time” fraction >99% of the observation time) was about 71%. Furthermore, we observed that the blinking behavior of the perovskite nanocrystals also could be regulated by directly mixing two different perovskite nanocrystals. These findings will provide new insights in realizing the full potential of these substances in photovoltaic and optoelectronic applications