Acta Chim. Sinica ›› 2019, Vol. 77 ›› Issue (1): 41-46.DOI: 10.6023/A18090374 Previous Articles     Next Articles



何通a,b, 杨晓峰a, 陈玉哲b, 佟振合b, 吴骊珠b   

  1. a 中北大学理学院 太原 030051;
    b 中国科学院理化技术研究所 光化学转换与功能材料重点实验室 北京 100190
  • 投稿日期:2018-09-06 发布日期:2018-10-23
  • 通讯作者: 陈玉哲, 吴骊珠, 杨晓峰;;
  • 基金资助:


Triplet-Triplet Annihilation Upconversion Based on Silica Nanoparticles

He Tonga,b, Yang Xiaofenga, Chen Yuzheb, Tong Zhenheb, Wu Lizhub   

  1. a School of Science, North University of China, Taiyuan 030051;
    b Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry CAS, Beijing 100190
  • Received:2018-09-06 Published:2018-10-23
  • Contact: 10.6023/A18090374;;
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21871280, 21474124), Ministry of Science and Technology (Nos. 2014CB239402 and 2017YFA0206903) and Chinese Academy of Sciences Strategic Pilot Science and Technology Project (Class B) (XDB17000000).

Photon upconversion based on triplet-triplet annihilation (TTA) composed of organic photosensitizer and emitter, has attracted widespread attention due to its unique photophysical properties and enormous applications in photovoltaic cells, photocatalysis, bio-imaging, and photodynamic therapy. Particularly, in biological systems, long-wavelength excitation light can efficiently reduce the interference of background fluorescence and increase the penetration depth of biological tissue, thereby avoiding the use of high-energy excitation light and reducing the damage to biological samples. However, most of the upconversion dyes based on TTA mechanism are water-insoluble organic compounds, which greatly limits their application in the biological field. Herein we synthesized a TTA upconversion system based on silica nanoparticles, which can achieve upconversion emission in water. Specifically, the photosensitizer (fluorinated tetraphenylporphyrin platinum) and the emitter (siloxane derivatized 9,10-diphenylanthracene) for photon upconversion were designed and synthesized, whose upconversion performance in dichloromethane solution was firstly studied by UV-Vis spectrophotometer and fluorescence spectrometer. Clear blue upconversion emission from emitter could be observed when the photosensitizer was excited by 532 nm laser. The triplet energy transfer efficiency between photosensitizer and emitter is 60%. The optimal ratio of photosensitizer to emitter was 1:40. Based on this ratio, the stable upconversion silica nanoparticles with uniform size in water were constructed by micellar template method. The average diameter characterized by transmission electron microscopy (TEM) is 15.5 nm and the hydration diameter characterized by dynamic light scattering (DLS) is 22.5 nm. When the 532 nm laser is used as the excitation source, the upconversion emission in water was achieved. Their upconversion luminescence lifetime and quantum yield are 12 μs and 0.8%, respectively. Finally, the upconversion mechanism in silica nanoparticles was studied. The upconversion intensities in silica nanoparticles show quadratic and first-order dependences on the incident intensity in the low and high excitation intensity ranges respectively, proving a triplet-triplet annihilation mechanism.

Key words: triplet-triplet annihilation, upconversion, silica nanoparticles, photosensitizer, emitter