Interface formation energy, bonding, energy band alignment in α-NaYF4 related core shell models: For future multi-layer core shell luminescence materials

Bolong HUANG, Hao DONG, Ka-Leung WONG*, Lingdong SUN, Chunhua YAN

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

To break through the bottle-neck of quantum yield in upconversion (UC) core-shell system, we elucidated that the energy transfer efficiency in core-shell system had an evident contribution from the charge transfer of interface with related to two factors: (1) band offsets and (2) binding energy area density. These two variables were determined by material intrinsic properties and core-shell thickness ratio. We further unraveled the mechanism of non-radiative energy transfer by charge transfer induced dipole at the interface, based on a quasi-classical derivation from Förster type resonant energy transfer (FRET) model. With stable bonding across the interface, the contributions on energy transfer in both radiative and non-radiative energy transfer should also be accounted together in Auzel's energy transfer (ETU) model in core-shell system. Based on the discussion about interface bonding, band offsets, and formation energies, we figured out the significance of interface bonding induced gap states (IBIGS) that played a significant role for influencing the charge transfer and radiative type energy transfer. The interface band offsets were a key factor in dominating the non-radiative energy transfer, which was also correlated to core-shell thickness ratio. We found that the energy area density with related to core/shell thickness ratio followed the trend of Boltzman sigmoidal growth function. By the physical trend, this work contributed a reference how the multi-layered core-shell structure was formed starting from the very beginning within minimum size. A route was paved towards a systematic study of the interface to unveil the energy transfer mechanism in core-shell systems.

Original languageEnglish
Pages (from-to)315-334
Number of pages20
JournalJournal of Rare Earths
Volume35
Issue number4
DOIs
Publication statusPublished - 1 Apr 2017

Scopus Subject Areas

  • Chemistry(all)
  • Geochemistry and Petrology

User-Defined Keywords

  • band-offset
  • core-shell
  • energy-transfer
  • interface
  • rare earths

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