Magnetic field insensitive photoluminescence decay of ZnSe/CdS core/shell type-II colloidal quantum dots
Abstract
We have synthesized ZnSe/CdS core/shell type-II colloidal quantum dots, where an electron and a hole are separated in the CdS shell and the ZnSe core, respectively. Our theoretical model has revealed that absorbance spectrum of bare ZnSe quantum dots in 2 nm radius becomes broadened with a large redshift (∼1.15 eV) when the electron in ZnSe core is separated by 3.2 nm CdS shell. Also, we found that our type-II QDs are insensitive to an external magnetic field up to 5 T in terms of central emission energy, degree of polarization, and photoluminescence decay time. This can be attributed to the electron-hole charge separation in a type-II structure, whereby the suppressed exchange interaction gives rise to a magnetic insensitivity with a small energy difference between the bright and dark exciton states.
- Publication:
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Japanese Journal of Applied Physics
- Pub Date:
- June 2018
- DOI:
- 10.7567/JJAP.57.06HE06
- Bibcode:
- 2018JaJAP..57fHE06L