Molecularly Dispersed Donors in Acceptor Molecular Crystals for Photon Upconversion under Low Excitation Intensity

Masanori Hosoyamada, Nobuhiro Yanai, Taku Ogawa, Nobuo Kimizuka

    Research output: Contribution to journalArticlepeer-review

    46 Citations (Scopus)


    For real-world applications of photon upconversion based on the triplet-triplet annihilation (TTA-UC), it is imperative to develop solid-state TTA-UC systems that work effectively under low excitation power comparable to solar irradiance. As an approach in this direction, aromatic crystals showing high triplet diffusivity are expected to serve as a useful platform. However, donor molecules inevitably tend to segregate from the host acceptor crystals, and this inhomogeneity results in the disappointing performance of crystalline state TTA-UC. In this work, a series of cast-film-forming acceptors was developed, which provide both regular acceptor alignment and soft domains of alkyl chains that accommodate donor molecules without segregation. A typical triplet sensitizer, PtII octaethylporphyrin (PtOEP), was dispersed in these acceptor crystals without aggregation. As a result, efficient triplet energy transfer from the donor to the acceptor and diffusion of triplet excitons among regularly aligned anthracene chromophores occurred. It resulted in TTA-UC emission at low excitation intensities, comparable to solar irradiance. Overcoming donor aggregation: A long-standing problem of aromatic-crystal-based photon upconversion (UC), donor aggregation in the acceptor crystal, is solved herein by modifying the acceptor with multiple alkyl chains. This improved the donor-to-acceptor energy-transfer efficiency, leading to effective UC processes even at low excitation intensities comparable to solar irradiance (see figure).

    Original languageEnglish
    Pages (from-to)2060-2067
    Number of pages8
    JournalChemistry - A European Journal
    Issue number6
    Publication statusPublished - Feb 5 2016

    All Science Journal Classification (ASJC) codes

    • Catalysis
    • Organic Chemistry


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