Type-II CdSe/CdTe/ZnTe (core-shell-shell) quantum dots with cascade band edges: The separation of electron (at CdSe) and hole (at ZnTe) by the CdTe layer

Chun Yen Chen*, Chiu Ting Cheng, Chih Wei Lai, Ya Hui Hu, Pi Tai Chou, Yi Hsuan Chou, Hsin-Tien Chiu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

The rational design and synthesis of CdSe/CdTe/ZnTe (core-shell-shell) type-II quantum dots are reported. Their photophysical properties are investigated via the interband CdSe→ZnTe emission and its associated relaxation dynamics. In comparison to the strong CdSe (core only) emission (λmax≈550 nm, Φf≈0.28), a moderate CdSe→CdTe emission (λmax≈1026 nm, Φf, ≈ 1.2 × 10-3) and rather weak CdSe→ZnTe interband emission (λmax≈1415 nm, Φf≈1.1 × 10-5) are resolved for the CdSe/CdTe/ ZnTe structure (3.4/1.8/1.3 nm). Capping CdSe/CdTe with ZnTe results in a distant electron-hole separation between CdSe (electron) and Zn Te (hole) via an intermediate CdTe layer. In the case of the CdSe/CdTe/ ZnTe structure, a lifetime as long as 150 ns is observed for the CdSe→ZnTe (1415 nm) emission. This result further indicates an enormously long radiative lifetime of ≈ 10ms. Upon excitation of the CdSe/CdTe/ ZnTe structure, the long-lived charge separation may further serve as an excellent hole carrier for catalyzing the redox oxidation reaction.

Original languageEnglish
Pages (from-to)1215-1220
Number of pages6
JournalSmall
Volume1
Issue number12
DOIs
StatePublished - 1 Dec 2005

Keywords

  • Colloids
  • Core-shell materials
  • Quantum dots
  • Semiconductors
  • Time-resolved spectroscopy

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