Toward 95.5% Efficient Red Emissive Carbon Dots: Oxidation State Enhancing Radiative Electron-Transition of Indole Fluorophore.

Red fluorescence carbon dots (CDs) are promising for diverse applications and have attracted tremendous research interest. However, it is still challenging to achieve red fluorescence CDs with high fluorescence quantum yields (QYs > 50%). Herein, three kinds of red fluorescence CDs with QYs of 53.

Activating One/Two-Photon Excited Red Fluorescence on Carbon Dots: Emerging n→π Photon Transition Induced by Amino Protonation.

Due to the complicated nature of carbon dots (CDs), fluorescence mechanism of red fluorescent CDs is still unrevealed and features highly controversial. Reliable and effective strategies for manipulating the red fluorescence of CDs are urgently needed. Herein, CDs with one-photon excited (622 nm, QYs ≈ 17%) and two-photon (629 nm) excited red fluorescence are prepared by acidifying o-phenylenediamine-based reaction sediments.