Charge transfer-mediated fluorescence kinetics of yellow AIE carbon-dots for solid-state optoelectronic applications

Carbon dots (CDs) are promising luminescent materials but often suffer from aggregation-caused quenching (ACQ) in the solid-state. Here, we report the synthesis of yellow-emissive CDs (Y-CDs) with aggregation-induced emission (AIE) behavior via a rapid microwave-assisted method. The as-prepared Y-CDs exhibit a solid-state photoluminescence quantum yield (PLQY) of 20.34%. Compared to their behaviors in the solution-state, Y-CDs exhibit an enhanced fluorescence in the solid-state, which is typically due to the suppressed non-radiative recombination resulting from control of the surface-state vibration. Our research indicates that this behavior is also related to the enhanced intrinsic radiative rate. Theoretical calculations suggest that charge transfer interactions in aggregates can enhance the oscillator strength and transition dipole moments associated with the S₁ → S₀ emissive transition. Such modulation of electronic transition parameters facilitates a more efficient radiative pathway, which is supported by time-resolved photoluminescence (TRPL) measurements. Furthermore, a yellow light-emitting diode (LED) based on Y-CDs achieves CIE coordinates of (0.48, 0.50). This study not only deepens the understanding of fluorescence kinetics in AIE systems but also offers a strategy for the development of efficient solid-state luminescent materials for optoelectronic applications.