Molecular Engineering of Chromophores to Enable Triplet-Triplet Annihilation Upconversion

Kealan J. Fallon, Emily M. Churchill, Samuel N. Sanders, James Shee, John L. Weber, Rinat Meir, Steffen Jockusch, David R. Reichman, Matthew Y. Sfeir, Daniel N. Congreve, Luis M. Campos

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


Triplet-triplet annihilation upconversion (TTA-UC) is an unconventional photophysical process that yields high-energy photons from low-energy incident light and offers pathways for innovation across many technologies, including solar energy harvesting, photochemistry, and optogenetics. Within aromatic organic chromophores, TTA-UC is achieved through several consecutive energy conversion events that ultimately fuse two triplet excitons into a singlet exciton. In chromophores where the singlet exciton is roughly isoergic with two triplet excitons, the limiting step is the triplet-triplet annihilation pathway, where the kinetics and yield depend sensitively on the energies of the lowest singlet and triplet excited states. Herein we report up to 40-fold improvements in upconversion quantum yields using molecular engineering to selectively tailor the relative energies of the lowest singlet and triplet excited states, enhancing the yield of triplet-triplet annihilation and promoting radiative decay of the resulting singlet exciton. Using this general and effective strategy, we obtain upconversion yields with red emission that are among the highest reported, with remarkable chemical stability under ambient conditions.

Original languageEnglish
Pages (from-to)19917-19925
Number of pages9
JournalJournal of the American Chemical Society
Issue number47
StatePublished - 25 Nov 2020
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 American Chemical Society.


L.M.C. thanks the Camille and Henry Dreyfus Foundation and NSF CAREER (DMR-1351293). D.N.C. and S.N.S. acknowledge the support of the Rowland Fellowship at the Rowland Institute at Harvard. K.J.F. thanks and acknowledges funding by the U.S.–U.K. Fulbright Commission and Lloyd’s Tercentenary Research Foundation. E.M.C. thanks the NSF GRFP (Grant No. 1644869). S.N.S. thanks the Arnold and Mabel Beckman Foundation for funding. R.M. thanks the U.S.–Israel Educational Foundation and Fulbright Program for funding. D.R.R. acknowledges the support of NSF-CHE 1954791.

FundersFunder number
Fulbright Program
U.S.–Israel Educational Foundation
U.S.–U.K. Fulbright Commission
National Science Foundation1954791, DMR-1351293
Arnold and Mabel Beckman Foundation
Camille and Henry Dreyfus Foundation
Rowland Institute at Harvard
Lloyd's Tercentenary Research Foundation1644869


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