Pd–Porphyrin Oligomers Sensitized for Green‐to‐Blue Photon Upconversion: The More the Better? |
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| Authors: | Dr Zhiqing Xun Dr Yi Zeng Dr Jinping Chen Dr Tianjun Yu Dr Xiaohui Zhang Prof?Dr Guoqiang Yang Prof?Dr Yi Li |
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| Affiliation: | 1. Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing, P.R. China;2. Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Beijing, P.R. China |
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| Abstract: | A series of directly meso‐meso‐linked Pd–porphyrin oligomers (PdDTP‐M, PdDTP‐D, and PdDTP‐T) have been prepared. The absorption region and the light‐harvesting ability of the Pd–porphyrin oligomers are broadened and enhanced by increasing the number of Pd–porphyrin units. Triplet–triplet annihilation upconversion (TTA‐UC) systems were constructed by utilizing the Pd–porphyrin oligomers as the sensitizer and 9,10‐diphenylanthracene (DPA) as the acceptor in deaerated toluene and green‐to‐blue photon upconversion was observed upon excitation with a 532 nm laser. The triplet–triplet annihilation upconversion quantum efficiencies were found to be 6.2 %, 10.5 %, and 1.6 % for the PdDTP‐M]/DPA, PdDTP‐D]/DPA, and PdDTP‐T]/DPA systems, respectively, under an excitation power density of 500 mW cm?2. The photophysical processes of the TTA‐UC systems have been investigated in detail. The higher triplet–triplet annihilation upconversion quantum efficiency observed in the PdDTP‐D]/DPA system can be rationalized by the enhanced light‐harvesting ability of PdDTP‐D at 532 nm. Under the same experimental conditions, the PdDTP‐D]/DPA system produces more 3DPA* than the other two TTA‐UC systems, benefiting the triplet–triplet annihilation process. This work provides a useful way to develop efficient TTA‐UC systems with broad spectral response by using Pd–porphyrin oligomers as sensitizers. |
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| Keywords: | energy transfer light harvesting sensitizers triplet– triplet annihilation upconversion |
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