Influence of Eu doping on the structural and optical properties of Zn1-xEuxSe quantum dots. (January 2021)

• Record Type: Journal Article
• Authors: Hien, N.T.; Yu, Y.Y.; Park, K.C.; Ca, N.X.; Chi, T.T.K.; Hien, B.T.T.; Thanh, L.D.; Do, P.V.; Tan, P.M.; Ha, P.T.T.
• Is Part Of: Journal of physics and chemistry of solids. Volume 148(2021)
• Publication Date: 2021-01
• Subjects: Zn1-xEuxSe quantum dots -- Structural transition -- Optical properties; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2020.109729
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: We have successfully fabricated Zn1-x Eux Se ( x = 0–0.1) quantum dots (QDs) with an average size of ~5 nm. X-ray diffraction analyses indicated that the zincblende-wurtzite structural transition occurred around x = 0.05. This leads to a small change in value of the band-gap energy E g from 3.13 eV for x = 0–3.03 eV for x = 0.1. By studying their photoluminescence (PL) spectra, we observed two emission regions. The first one around 400–415 nm is a broad peak associated with the band-edge emission, while the other consists of sharp peaks due to the electronic transitions ( 5 D0 - 7 F j, j = 0–4) of Eu 3+ ions in the ZnSe host lattice. Similar to the variation tendency of E g, the excitonic emission peak also shifts towards low energies when x increases. Among the 5 D0 - 7 F j transitions, the radiative transition with j = 2 peaked at 618 nm has the strongest intensity, particularly for x = 008. Time-resolved PL spectra of both emission regions can be described by a multi-exponential decay function. The average time constants of the Eu 3+ -related emission at 618 nm vary in the range of 2.4–4.8 ms, which is much longer than those recorded for the band-edge emission. We also analyzed the emission features of QDs through the CIE chromaticity coordinates and found the QDs with x = 0.08, showing neutral white light. Highlights: The emissions associated with 5 D0 - 7 Fj ( j = 0–4) transitions of Eu 3+ were observed in the PL spectra of Zn1-x Eux Se QDs. Crystal-structure change in Zn1-x Eux Se QDs from ZB to WZ was observed as x > 0.05. Steady-state and time-resolved PL studies reveal an effective ZnSe QDs-to-Eu 3+ energy transfer process. White light-tunable emissions. Zn1-x Eux Se QDs are potential materials for photovoltaic, photocatalyst, biosensing and white light-emitting devices.