Interface formation energy,bonding,energy band alignment in α-NaYF4 related core shell models:For future multi-layer core shell luminescence materials
来源期刊:JOURNAL OF RARE EARTHS2017年第4期
论文作者:黄勃龙 董浩 Wong Ka-Leung 孙聆东 严纯华
文章页码:315 - 334
摘 要: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 F?rster 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.
黄勃龙1,董浩2,Wong Ka-Leung3,孙聆东2,严纯华2
1. Department of Applied Biology and Chemical Technology,The Hong Kong Polytechnic University2. Beijing National Laboratory for Molecular Sciences,State Key Laboratory of Rare Earth Materials Chemistry and Applications,PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry,College of Chemistry and Molecular Engineering,Peking University3. Department of Chemistry,Hong Kong Baptist University
摘 要: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 F?rster 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.
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