基于不同结构半导体-金属异质纳米颗粒调控Er3+掺杂薄膜荧光和上转换发光特性的研究

The erbium(Er) doped materials are of great interest for application such as lasers,three-dimensional display, and biological fluorescence imaging. However, the photo absorption cross section of Er3+ is very small due to the dipole-forbidden nature of the intra-4f transitions and, thus, the intensity of the luminescence is relatively low. The small absorption cross sections of Er3+ have become a limitation to the optimization of such materials for optical amplification and, therefore, a number of methods have been proposed to increase the emission efficiency of Er3+. All these force us to find new method to enhance the emission of Er3+ in the different host materials. Recently another promising choice is to use the Local Surface Plasmon Resonance (LSPR) of noble metal nanoparticles to enhance the emission efficiency. However, the enhancement is limited by the heat stability of metal nanoparticles. During the project, We would (1) introduce the semiconductor-metal nanoparticles with different shapes into the Er3+ doped films,(2) enhance the fluorescence at 1540nm and the up-conversion luminescence of Er3+ at visible bands for the different host materials, impede the processes that are unfavorable for the emission, and (3) investigate the sensibility of the tansitions to the variation in local environments, the control on the radiative decay rate, non-radiative decay rate, energy transfer and quantum efficiency of Er3+ by the semiconductor-metal nanopartilces. And set up the theory model. The project would greatly enhance the emission of Er3+ at the different wavelengths, and the semiconductor-metal nanoparticles would suggest a new pathway for tailoring the luminescence properties in Er3+ doped materials.

Er3+能级丰富，在光通信、三维显示技术、生物荧光图像、激光等领域应用广泛。由于Er3+吸收属4f层内窄带电子跃迁，吸收截面很小，这就使得Er3+存在发光效率低的缺点。利用金属纳米颗粒的局域等离子体共振（LSPR）效应可以明显提高Er3+的发光，然而增强效果又受到颗粒稳定性差的限制。本项目拟开展以下三个方面的研究：（1）将半导体作为保护层和间隔层，实现稳定性较好的半导体-金属异质纳米颗粒在Er3+发光薄膜中的掺杂；（2）实验方面，利用异质纳米颗粒可调的局域表面等离子体共振（LSPR）效应，在不同基质环境下增强Er3+1540nm荧光和可见波段上转换发光，抑制其他对发光不利的过程，实现对特定波段发光的可控性增强；（3）理论方面，探索异质纳米颗粒对Er3+辐射过程中伴随的能量传递、无辐射弛豫、上转换等的调制，建立合适的理论模型。本项目的实施将显著地提高Er3+的发光和激光效率。

稀土离子能级丰富，在光通信、三维显示技术、生物荧光图像、激光等领域应用广泛。由于稀土离子吸收属于4f层内窄带电子跃迁，吸收截面很小，这就使得稀土离子存在发光效率低的缺点。本项目利用金属纳米颗粒的局域等离子体共振（LSPR）效应明显提高了稀土离子的发光，具体开展了以下三个方面的研究：（1）实现了纳米颗粒与稀土发光薄膜的结合；（2）实验方面，利用球形和多面体结构银纳米颗粒、棒形金纳米颗粒和具有SiO2包层的棒形核壳异质纳米颗粒，在不同基质环境下系统研究了颗粒对Eu发光特性的调控；最大增强效果可达263倍；（3）理论方面，研究了纳米颗粒对Eu辐射过程中伴随的能量传递、无辐射弛豫等的调制；本项目的实施显著提高了Eu离子的发光和激发效率。