Scalable Synthesis of Green Fluorescent Carbon Dot Powders with Unprecedented Efficiency

Abstract It still remains a challenge to synthesize solid‐state carbon dots (CDs) with high emission efficiency; a hurdle that has hindered the application of CDs in many fields. In this work, efficient fluorescent CDs have been prepared through a one‐step microwave‐assisted heating method. Experimental data show strong green emissions produced from the CD powders (CDPs), carrying an unprecedented 75.9% quantum yield due to both spatial confinement and defect reduction with the introduction of NaOH. Likewise, CDPs prepared in tens of grams at 3 min time intervals also achieve high production yields at ≈69.8%. Specifically, for white light‐emitting devices (WLEDs) with color coordinates of 0.366 and 0.366, when fabricated by coating CDPs with commercial red‐emitting phosphors on blue‐emitting LED chips, it is found that the luminous efficiency reached 52.3 lm W⁻¹. Besides, the WLEDs exhibit a high color rendering index of 93.5 and show great color chromatic stability even at a driving current of 200 mA.