Gram‐Scale Synthesis of 41% Efficient Single‐Component White‐Light‐Emissive Carbonized Polymer Dots with Hybrid Fluorescence/Phosphorescence for White Light‐Emitting Diodes

Fluorescent carbon dots (CDs) are compelling optical emitters to construct white light-emitting diodes (WLEDs). However, it remains a challenge to achieve large-scale and highly efficient single-component white-light-emissive CDs suitable for WLED applications. Herein, a low cost, fast processable, environmentally friendly, and one-step synthetic approach is developed for the preparation of gram-scale and highly efficient single-component white-light-emissive carbonized polymer dots (SW-CPDs). It is revealed that hybrid fluorescence/phosphorescence components cooperatively contribute to the emergence of white light emission. The SW-CPDs exhibit a record quantum yield (QY) of ≈41% for the white light emission observed in solid-state CD systems, while the QY of the phosphorescence is ≈23% under ambient conditions. Heavy doping of N and P elements as well as presence of covalently cross-linked polymer frameworks is suggested to account for the emergence of hybrid fluorescence/phosphorescence, which is supported by the experimental results and theoretical calculations. A WLED is fabricated by applying the SW-CPDs on an UV-LED chip, showing favorable white-light-emitting characteristics with a high luminous efficacy of 18.7 lm W-1 that is comparable to that of state-of-the-art WLEDs reported before.