Semiconductor quantum dots of the A2B6 group and organic semiconductors have been widely studied and applied in optoelectronics. This study aims to combine CdTe quantum dots and perylene-based dye molecules into advanced nanostructure system targeting to improve their functional properties. In such systems, new electronic states, a mixture of Wannier–Mott excitons with charge-transfer excitons, have appeared at the interface of CdTe quantum dots and the perylene dye. The nature of such new states has been analyzed by absorption and photoluminescence spectroscopy with picosecond time resolution. Furthermore, aggregation of perylene dye on the CdTe has been elucidated, and contribution of Förster resonant energy transfer has been observed between aggregated forms of the dye and CdTe quantum dots in the hybrid CdTe-perylene nanostructures. The studied nanostructures have strongly quenched emission of quantum dots enabling potential application of such systems in dissociative sensing.

Anti-Kasha emission (i.e., the emission from S n (n > 1) excited levels) of infrared chromophores which possess intensive absorption and S1 emission in the near-infrared region, but which are spectrally silent in the visible, is a challenging task for relevant applications such as energy conversion, bioimaging, sensitization of solar cells, optical sensors, and so on. Here we demonstrate a dual emission of near-infrared tricarbocyanine dyes with a bright green S2 fluorescence, whose quantum yield increases by 2–4 times together with a strong enhancement of the spontaneous rate of S2 fluorescence, whereas the quantum yield of S1 emission decreases by 2–7 times, respectively, as a result of immobilization of the dye molecule via interaction with carbon quantum dots. The enhanced immobilization-induced S2 emission is shown to occur because of planarization of the molecule and freezing its rotational degrees of freedom as indicated by suppression of the dye hot-band absorption-assisted anti-Stokes S1 emission.

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