Manipulating the Cooling Bottleneck Through Quantum Confinement in Halide Perovskite Nanocrystals

Halide perovskites have recently been cast into the limelight for their potential in next-generation photovoltaic concepts such as hot carrier solar cells (HCSCs) [1]. The strong phonon bottleneck and high carrier temperatures in these materials make them excellent candidates for HCSCs. One way to further enhance these properties is through quantum confinement in halide perovskite nanocrystals or quantum dots, where an intrinsic cooling bottleneck can be induced due to the discretization of energy levels [2]. However, reports on the size dependence of the intrinsic cooling bottleneck in halide perovskite nanocrystals are still divergent. With advancements in methods to synthesize strongly confined perovskite nanocrystals recently, it is worthwhile to re-examine this effect [3]. In this talk, we attempt to rationalize these divergent observations. The size, shape, and composition effects on the cooling bottleneck will be discussed. Through independent ultrafast spectroscopy measurements, we show that the nature of the cooling bottleneck in halide perovskite nanocrystals can be tuned. Ultimately, we wish to provide a broad overview of the quantum confinement effects on this cooling bottleneck to resolve the existing controversy.<br/><br/><b>References</b><br/>1. Li, M., et al., <i>Slow Hot-Carrier Cooling in Halide Perovskites: Prospects for Hot-Carrier Solar Cells.</i> Advanced Materials, 2019: p. 1802486.<br/>2. Li, M., et al., <i>Slow cooling and highly efficient extraction of hot carriers in colloidal perovskite nanocrystals.</i> Nat. Commun., 2017. <b>8</b>(1): p. 1-10.<br/>3. Dey, A., et al., <i>State of the Art and Prospects for Halide Perovskite Nanocrystals.</i> ACS Nano, 2021. <b>15</b>(7): p. 10775-10981.