Dielectric Screening Modulates Semiconductor Nanoplatelet Excitons
Dielectric Screening Modulates Semiconductor Nanoplatelet Excitons
复制标题
介电屏蔽调制半导体纳米片激子
DOI：
10.1021/acs.jpclett.1c00624
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Caram, Justin R.
中科院分区：
文献类型：
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作者：
Shin, Ashley J.;Hossain, Azmain A.;Tenney, Stephanie M.;Tan, Xuanheng;Tan, Lauren A.;Foley, Jonathan J.;Atallah, Timothy L.;Caram, Justin R.
外部介电环境的影响是众所周知的二维半导体材料，但忽略了胶体生长的II-VI纳米片（NPL）。在这项工作中，我们合成MX（M = Cd，Hg; X = Se，Te）NPL的不同厚度和应用埃利奥特模型提取激子结合能报告值与以前的方法和扩展到较少研究碲化镉和汞硫属化物NPL的良好协议。我们发现，激子结合能调制的内部与外部的介电和半导体材料的厚度的相对效果。一个分析模型表明，介电屏蔽通过扭曲NPL表面的库仑势来增加激子相对于本体的结合能。我们进一步证实了这种效果，通过减少和恢复的激子结合能的碲化汞NPL通过在极化溶剂中洗涤。我们的研究结果表明，NPL是货车德瓦尔斯二维半导体的胶体类似物，并指出表面改性作为一种方法来控制电子物理学和器件性能。
The influence of external dielectric environments is well understood for 2D semiconductor materials but overlooked for colloidally grown II–VI nanoplatelets (NPLs). In this work, we synthesize MX (M = Cd, Hg; X = Se, Te) NPLs of varying thicknesses and apply the Elliott model to extract exciton binding energies—reporting values in good agreement with prior methods and extending to less studied cadmium telluride and mercury chalcogenide NPLs. We find that the exciton binding energy is modulated both by the relative effect of internal vs external dielectric and by the thickness of the semiconductor material. An analytical model shows dielectric screening increases the exciton binding energy relative to the bulk by distorting the Coulombic potential across the NPL surface. We further confirm this effect by decreasing and recovering the exciton binding energy of HgTe NPLs through washing in polarizable solvents. Our results illustrate NPLs are colloidal analogues of van der Waals 2D semiconductors and point to surface modification as an approach to control photophysics and device properties.