Philbin John P, Brumberg Alexandra, Diroll Benjamin T, Cho Wooje, Talapin Dmitri V, Schaller Richard D, Rabani Eran
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA.
J Chem Phys. 2020 Aug 7;153(5):054104. doi: 10.1063/5.0012973.
The ability to control both the thickness and the lateral dimensions of colloidal nanoplatelets offers a test-bed for area and thickness dependent properties in 2D materials. An important example is Auger recombination, which is typically the dominant process by which multiexcitons decay in nanoplatelets. Herein, we uncover fundamental properties of biexciton decay in nanoplatelets by comparing the Auger recombination lifetimes based on interacting and noninteracting formalisms with measurements based on transient absorption spectroscopy. Specifically, we report that electron-hole correlations in the initial biexcitonic state must be included in order to obtain Auger recombination lifetimes in agreement with experimental measurements and that Auger recombination lifetimes depend nearly linearly on the lateral area and somewhat more strongly on the thickness of the nanoplatelet. We also connect these scalings to those of the area and thickness dependencies of single exciton radiative recombination lifetimes, exciton coherence areas, and exciton Bohr radii in these quasi-2D materials.
控制胶体纳米片的厚度和横向尺寸的能力为研究二维材料中与面积和厚度相关的特性提供了一个试验平台。一个重要的例子是俄歇复合，它通常是纳米片中多激子衰变的主导过程。在此，我们通过比较基于相互作用和非相互作用形式的俄歇复合寿命与基于瞬态吸收光谱的测量结果，揭示了纳米片中双激子衰变的基本特性。具体而言，我们报告称，为了获得与实验测量结果一致的俄歇复合寿命，必须考虑初始双激子态中的电子 - 空穴相关性，并且俄歇复合寿命几乎与纳米片的横向面积呈线性关系，而对纳米片厚度的依赖性则稍强一些。我们还将这些标度关系与这些准二维材料中单激子辐射复合寿命、激子相干面积和激子玻尔半径的面积和厚度依赖性联系起来。
