Unravelling the energy transfer of Er3+-self-sensitized upconversion in Er3+–Yb3+–Er3+ clustered core@shell nanoparticles. Issue 46 (21st November 2017) - Huang, Bolong
Abstract : The interplay on enhancing and quenching effects between Er 3+ and Yb 3+ dopant clusters in self-sensitized core@shell nanoparticles is studied. Abstract : Unravelling upconversion (UC) energy transfer mechanisms is significant for designing novel efficient anti-Stokes phosphors. We have studied the correlation of different lanthanide dopants within Er 3+ -self-sensitized core@shell upconversion nanoparticles (UCNPs). Here, our focus will be on high-concentration dopants that are able to sufficiently produce the clustering effect, especially within the interplay between Er 3+ and Yb 3+ . We demonstrate that whatever the amount of the self-sensitizer ( e.g., Er 3+ ), abnormal absorption enhancement will occur as long as Yb 3+ clusters are present. This effect originates from the substantial energy transfer between Yb 3+ –Yb 3+ clusters despite the increased energy transfer from Yb 3+ to Er 3+ . Therefore, the energy transfer efficiency is still constrained. However, we conversely used one of the aforementioned quench-paths of UC energy transfer to easily transfer the energy from the in-shell shell layer to the in-core area with the assistance of the energy potential reservoir, which was given by the homogeneous core@shell band offset at the interface region. Indirectly, we actualize the Er 3+ UC luminescence with self-sensitization through an extended energy transfer path. This work provides a solid support and analytic theory for unraveling the energy transfer mechanism from recent works on Er 3+ self-sensitized UC luminescence.