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Transformation of Colloidal Quantum Dot: From Intraband Transition to Localized Surface Plasmon Resonance.
Nano Letters ( IF 9.6 ) Pub Date : 2020-06-04 , DOI: 10.1021/acs.nanolett.0c01080
Juhee Son 1 , Dongsun Choi 1 , Mihyeon Park 1 , Juyeong Kim 2 , Kwang Seob Jeong 1
Affiliation  

An increase in the carrier density of semiconductor nanocrystals can gradually change the origin of the optical property from the excitonic transition to the localized surface plasmon resonances. Here, we present the evolution of the electronic transition of self-doped Ag2Se colloidal quantum dots, from the intraband transition to the localized surface plasmon resonances along with a splitting of the intraband transition (1Pe–1Se). The minimum fwhm of the split intraband transition is only 23.7 meV, which is exceptionally narrow compared to that of metal oxide nanocrystals showing LSPRs, inferring that the electron–electron scattering is significantly suppressed due to the smaller carrier density. The splitting of the intraband transition mainly results from the asymmetrical crystal structure of the tetragonal Ag2Se CQDs and becomes distinct when the nanocrystal changes its crystal structure from the cubic to tetragonal structure. Maximizing the discrete energy levels in the quantum dot along with mixing with plasmonic characters may provide opportunities to fully harness merits of both the quantum confinement effect and localized surface plasmon resonance characters.

中文翻译:

胶体量子点的转变:从带内跃迁到局部表面等离振子共振。

半导体纳米晶体载流子密度的增加可以逐渐改变光学性质的起源,从激子跃迁到局部表面等离子体激元共振。在这里,我们介绍了自掺杂Ag 2 Se胶体量子点的电子跃迁的演化,从带内跃迁到局部表面等离振子共振以及带内跃迁的分裂(1P e –1S e)。分裂带内跃迁的最小fwhm仅23.7 meV,与显示LSPR的金属氧化物纳米晶体相比,其异常窄,这表明由于载流子密度较小,电子-电子散射得到了显着抑制。带内跃迁的分裂主要是由四方Ag 2 Se CQDs的不对称晶体结构引起的,当纳米晶体的晶体结构从立方结构变为四方结构时,带内过渡的分裂变得明显。最大化量子点中的离散能级以及与等离激元特征的混合可以提供充分利用量子约束效应和局部表面等离振子共振特征的优点的机会。
更新日期:2020-07-08
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