Construction of photoluminescence-afterglow dual-mode white emission materials from carbon dots via Förster resonance energy transfer

Carbon dots (CDs) have attracted much attention because of their unique structures and fascinating optical properties. In recent years, multicolor CDs have been realized through the efforts of researchers. However, it remains a challenge to obtain CDs with photoluminescence (PL)-afterglow dual-mode white emission, which limits the application of CDs in the field of light emitting diodes (LEDs). Herein, an effective strategy is designed to prepare both white PL and afterglow CDs (w-CDs), which is to combine (3-aminopropyl)triethoxysilane (APTES) and orange fluorescence CDs (o-CDs) as precursors through a hydrothermal reaction. During the synthesis of w-CDs, blue room temperature phosphorescence (RTP) CDs (b-CDs) formed using APTES were used as donors and o-CDs as acceptors. Depending on triplet-to-singlet Förster resonance energy transfer (FRET), dual-mode white light CDs with Commission Internationale de l’Eclairage (CIE) coordinates of (0.37, 0.37) for PL and (0.33, 0.37) for afterglow, and a PL quantum yield (PLQY) of 32.44% were successfully prepared. Importantly, by changing the ratio of o-CDs to b-CDs, the color temperature of the white afterglow can be easily adjusted from cold white to warm white. In addition, w-CDs have been successfully used in the fabrication of white LEDs (WLEDs) and dynamic displays, and can be applied to time-delay illumination and afterglow display.