Donor–Acceptor–Collector Ternary Crystalline Films for Efficient Solid-State Photon Upconversion

It is pivotal to achieve efficient triplet–triplet annihilation based photon upconversion (TTA-UC) in the solid-state for enhancing potentials of renewable energy production devices. However, the UC efficiency of solid materials is largely limited by low fluorescence quantum yields that originate from the aggregation of TTA-UC chromophores and also by severe back energy transfer from the acceptor singlet state to the singlet state of the triplet donor in the condensed state. In this work, to overcome these issues, we introduce a highly fluorescent singlet energy collector as the third component of donor-doped acceptor crystalline films, in which dual energy migration, i.e., triplet energy migration for TTA-UC and succeeding singlet energy migration for transferring energy to a collector, takes place. To demonstrate this scheme, a highly fluorescent singlet energy collector was added as the third component of donor-doped acceptor crystalline films. An anthracene-based acceptor containing alkyl chains and a carboxylic moiety is mixed with the triplet donor Pt­(II) octaethylporphyrin (PtOEP) and the energy collector 2,5,8,11-tetra-<i>tert</i>-butylperylene (TTBP) in solution, and simple spin-coating of the mixed solution gives acceptor films of nanofibrous crystals homogeneously doped with PtOEP and TTBP. Interestingly, delocalized singlet excitons in acceptor crystals are found to diffuse effectively over the distance of ∼37 nm. Thanks to this high diffusivity, only 0.5 mol % of doped TTBP can harvest most of the singlet excitons, which successfully doubles the solid-state fluorescent quantum yield of acceptor/TTBP blend films to 76%. Furthermore, since the donor PtOEP and the collector TTBP are separately isolated in the nanofibrous acceptor crystals, the singlet back energy transfer from the collector to the donor is effectively avoided. Such efficient singlet energy collection and inhibited back energy transfer processes result in a large increase of UC efficiency up to 9.0%, offering rational design principles toward ultimately efficient solid-state upconverters

Demographic characteristics of patients according to pre-exposure rabies prophylaxis (N = 322).

Demographic characteristics of patients according to pre-exposure rabies prophylaxis (N = 322).</p

Number of patients with animal exposure according to destination (N = 322).

Number of patients with animal exposure according to destination (N = 322).</p

Characteristics of animal exposure according to animal type (N = 322).

Characteristics of animal exposure according to animal type (N = 322).</p

The Kaplan–Meier curve showing the proportion of exposure-free patients from time of departure according to animal type.

Lines indicate dogs (solid black), cats (dotted red), monkeys (solid blue), and others (dotted green).</p

Countries where exposure occurred according to animal type.

Countries with the highest number of patients exposed to dogs, cats, and monkeys are shown in descending order.</p