Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
ACS Nano. 2012 Oct 23;6(10):8758-66. doi: 10.1021/nn302466r. Epub 2012 Sep 11.
We have demonstrated amplification of luminescence in upconversion nanophosphors (UCNPs) of hexagonal phase NaYF(4) (β-NaYF(4)) doped with the lanthanide dopants Yb(3+), Er(3+) or Yb(3+), Tm(3+) by close proximity to metal nanoparticles (NPs). We present a configuration in which close-packed monolayers of UCNPs are separated from a dense multilayer of metal NPs (Au or Ag) by a nanometer-scale oxide grown by atomic layer deposition. Luminescence enhancements were found to be dependent on the thickness of the oxide spacer layer and the type of metal NP with enhancements of up to 5.2-fold proximal to Au NPs and of up to 45-fold proximal to Ag NPs. Concomitant shortening of the UCNP luminescence decay time and rise time is indicative of the enhancement of the UCNP luminescence induced by resonant plasmonic coupling and nonresonant near-field enhancement from the metal NP layer, respectively.
我们已经证明，通过接近金属纳米粒子（NPs），掺杂镧系元素掺杂剂 Yb(3+)、Er(3+) 或 Yb(3+)、Tm(3+)的六方相 NaYF(4)（β-NaYF(4)）上转换纳米荧光粉（UCNPs）的发光可以得到增强。我们提出了一种结构，其中紧密堆积的 UCNP 单层通过原子层沉积生长的纳米级氧化物与密集的多层金属 NPs（Au 或 Ag）隔开。发现发光增强取决于氧化物间隔层的厚度和金属 NP 的类型，与 Au NPs 相邻时增强高达 5.2 倍，与 Ag NPs 相邻时增强高达 45 倍。UCNP 发光衰减时间和上升时间的同时缩短表明 UCNP 发光的增强分别是由共振等离子体耦合和金属 NP 层的非共振近场增强引起的。
