Oriel Evan H, Dirin Dmitry N, Shcherbak Kseniia, Bodnarchuk Maryna I, Kovalenko Maksym V, Chen Lin X, Schaller Richard D
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States.
Laboratory of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland.
J Phys Chem Lett. 2024 Jun 13;15(23):6062-6068. doi: 10.1021/acs.jpclett.4c00941. Epub 2024 May 31.
Semiconductor nanocrystals (NCs) with size-tuned energy gaps present unique and desirable properties for optoelectronic applications. Recent synthetic advancements offer routes to spheroidal CsPbBr perovskite NCs in the strong quantum confinement regime with narrow size dispersion. Using tunable femtosecond laser pulses, we examine intraband carrier relaxation using transient absorption spectroscopy and show that, across the transition from weak to strong confinement, hot carrier lifetime increases compared to larger bulk-like particles. However, further increases of confinement subsequently lead to a reduction of the hot carrier lifetime and increase of the non-radiative Auger recombination rate. Finally, we show that hot carrier lifetimes increase as a function of excess energy above the band gap less sensitively under high confinement in comparison to the bulk. Understanding such unique trends is important for maximizing hot carrier lifetimes for use in next-generation hot carrier devices as well as evaluating the transition from weak to strong confinement.
具有尺寸可调能隙的半导体纳米晶体（NCs）在光电子应用中展现出独特且理想的性质。近期的合成进展为处于强量子限制 regime 且尺寸分散窄的球形 CsPbBr 钙钛矿 NCs 提供了制备途径。利用可调谐飞秒激光脉冲，我们通过瞬态吸收光谱研究带内载流子弛豫，并表明，在从弱限制到强限制的转变过程中，与较大的类体相粒子相比，热载流子寿命增加。然而，限制的进一步增加随后导致热载流子寿命降低以及非辐射俄歇复合率增加。最后，我们表明，与体相相比，在高限制下热载流子寿命随带隙以上多余能量的函数增加不太敏感。理解这种独特趋势对于最大化用于下一代热载流子器件的热载流子寿命以及评估从弱限制到强限制的转变很重要。
