Organic J-Aggregate Nanodots with Enhanced Light Absorption and Near-Unity Fluorescence Quantum Yield

Development of biocompatible fluorophores with small size, bright fluorescence, and narrow spectrum translate directly into major advances in fluorescence imaging related techniques. Here, we discover that a donor–acceptor–donor-type organic molecule consisting carbazole (Cz) donor benzothiazole (BT) acceptor (CzBTCz) assembles quasi-crystalline J-aggregates upon formation ultrasmall nanoparticles. The 3.5 nm CzBTCz Jdots show absorption (fwhm = 27 nm), near-unity quantum yield (?fl 0.95), enhanced peak molar extinction coefficient. superior spectroscopic characteristics the result two orders magnitude brighter photoluminescence compared semiconductor dots, which enables continuous single-Jdots over 1 h period. Comparison structurally similar CzBT nanoparticles demonstrates critical role played by shape on Jdots. Our findings open an avenue for development new class fluorescent based J-aggregates.