Competition between zero-phonon and phonon-assisted luminescence in colloidal CdSe quantum dots

被引：37

作者：

Wijnen, F. J. P. ^{[1
]}

Blokland, J. H. ^{[1
]}

Chin, P. T. K. ^{[2
]}

Christianen, P. C. M. ^{[1
]}

Maan, J. C. ^{[1
]}

机构：

[1] Radboud Univ Nijmegen, Inst Mol & Mat, High Field Magnet Lab, NL-6525 ED Nijmegen, Netherlands

[2] Eindhoven Univ Technol, NL-5600 MB Eindhoven, Netherlands

来源：

PHYSICAL REVIEW B | 2008年 / 78卷 / 23期

关键词：

cadmium compounds; colloids; excitons; II-VI semiconductors; nanostructured materials; phonons; photoluminescence; red shift; semiconductor quantum dots; surface states; wide band gap semiconductors;

D O I：

10.1103/PhysRevB.78.235318

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We determine the low-temperature optical properties of dark-exciton states in CdSe/CdS nanocrystal quantum dots (NQDs). By using resonant laser excitation we distinguish zero-phonon from phonon-assisted photoluminescence. The NQDs show a decreasing zero-phonon intensity with decreasing temperature, resulting in a redshift of the nonresonant photoluminescence. This redshift is undone by application of a magnetic field. Our results show that dark-exciton luminescence originates from the intricate competition of phonon-assisted and zero-phonon transitions, the latter of which are enhanced by dark-bright-exciton mixing due to unpassivated surface states or a magnetic field.

引用

页数：5

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