Employing Core-Shell Quantum Dots as Triplet Sensitizers for Photon Upconversion

Keisuke Okumura, Kazuma Mase, Nobuhiro Yanai, Nobuo Kimizuka

    Research output: Contribution to journalArticlepeer-review

    80 Citations (Scopus)


    A new family of surface-functionalized CdSe/ZnS core-shell quantum dots (csQD) has been developed, which work as triplet sensitizers for triplet-triplet annihilation-based photon upconversion (TTA-UC). The surface modification of csQD with acceptor molecules plays a key role in the efficient relay of the excited energy of csQD to emitter molecules in the bulk solution, where the generated emitter triplets undergo triplet-triplet annihilation that leads to photon upconversion. Interestingly, improved UC properties were achieved with the core-shell QDs compared with core-only CdSe QDs (cQD). The threshold excitation intensity, which is defined as the necessary irradiance to achieve efficient TTA process, decreases by more than a factor of four. Furthermore, the total UC quantum yield is enhanced more than 50-fold. These enhancements should be derived from better optical properties of csQD, in which the non-radiative surface recombination sites are passivated by the shell layer with wider bandgap.

    Original languageEnglish
    Pages (from-to)7721-7726
    Number of pages6
    JournalChemistry - A European Journal
    Issue number23
    Publication statusPublished - Jun 1 2016

    All Science Journal Classification (ASJC) codes

    • Catalysis
    • Organic Chemistry


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