Anthracene Diphosphate Ligands for CdSe Quantum Dots; Molecular Design for Efficient Upconversion

De Roo, Jonathan; Huang, Zhiyuan; Schuster, Nathaniel J.; Hamachi, Leslie S.; Congreve, Daniel N.; Xu, Zihao; Xia, Pan; Fishman, Dmitry A.; Lian, Tianquan; Owen, Jonathan S.; Tang, Ming Lee

doi:10.1021/acs.chemmater.9b04294

DOE OSTI · 1773896

Anthracene Diphosphate Ligands for CdSe Quantum Dots; Molecular Design for Efficient Upconversion

De Roo, Jonathan·Huang, Zhiyuan·Schuster, Nathaniel J.·Hamachi, Leslie S.·Congreve, Daniel N.·Xu, Zihao·Xia, Pan·Fishman, Dmitry A.·Lian, Tianquan·Owen, Jonathan S.·Tang, Ming Lee

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Abstract

Quantum dot (QD)-sensitized photon upconversion follows a multi-step energy transfer process from the QD to transmitter ligand to a soluble annihilator. Using a novel 10-R-anthracene-1,8-diphosphoric acid (R = octyl, 2- hexyldecyl, phenyl) ligand with high binding affinity for CdSe QD surfaces, we demonstrate a photon upconversion process that is limited by the transmitter to annihilator transfer efficiency. Using 1 H NMR spectroscopy, we demonstrate that these bidentate diphosphate ligands rapidly and irreversibly displace two carboxylate ligands. These ligands mediate energy transfer from the photoexcited QDs to a triplet annihilator (1,10-diphenylanthracene), producing overall photon upconversion quantum efficiencies as high as 17%, the highest for QDs with no shells. In conclusion, transient absorption spectroscopy shows that the anthracene dihydrogen phosphate (ADP) ligand supports a 3.4 fold longer triplet state lifetime compared to 9-anthracene carboxylic acid (299.9 ± 9.5 vs 88.2 ± 2.1 μs), increasing the probability of energy transfer.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY Cadmium selenide Energy transfer Ligands Luminescence Quantum dots

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De Roo, Jonathan, Huang, Zhiyuan, Schuster, Nathaniel J., Hamachi, Leslie S., Congreve, Daniel N., Xu, Zihao, Xia, Pan, Fishman, Dmitry A., Lian, Tianquan, Owen, Jonathan S., Tang, Ming Lee. 2020-01-23. Anthracene Diphosphate Ligands for CdSe Quantum Dots; Molecular Design for Efficient Upconversion. https://doi.org/10.1021/acs.chemmater.9b04294

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