Excimer-Mediated Intermolecular Charge Transfer in Self-Assembled Donor-Acceptor Dyes on Metal Oxides

Yongze Yu, Szu Chia Chien, Jiaonan Sun, Elline C. Hettiaratchy, Roberto C. Myers, Li Chiang Lin, Yiying Wu

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


When conjugate molecules are self-assembled on the surface of semiconductors, emergent properties resulting from the electronic coupling between the conjugate moieties are of importance in the interfacial electron-transfer dynamics for photoelectrochemical and optoelectronics devices. In this work, we investigate the self-assembly of triphenylamine-oligothiophene-perylenemonoimide (PMI) molecules, denoted as BH4, on metal oxide surfaces via UV-vis absorption, photoluminescence, and transient near-infrared absorption spectroscopies and molecular dynamics simulations, and we report the excimer formation due to the π-πinteraction of the PMI units between the neighboring dye molecules. To our best knowledge, this is the first experimental observation of intermolecular excimer formation when conjugate donor-acceptor molecules form a self-assembled monolayer. In addition, a long-lived (4.3 μs) intermolecular charge separation is observed, and a new excimer-mediated intermolecular charger-transfer mechanism is proposed. This work demonstrates that, through the design of dye molecules, the excited complexes or aggregates can provide a pathway to slow down the recombination rate in photoelectrodes that utilize donor-acceptor dyad molecules.

Original languageEnglish
Pages (from-to)8727-8731
Number of pages5
JournalJournal of the American Chemical Society
Issue number22
StatePublished - 5 Jun 2019


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