Versatile Dual-Emissive Boron-Nitrogen Co-Doped carbon Dots: Unlocking efficient electroluminescent Light-Emitting diodes with breakthrough EQE Approaching 7%

Carbon dots (CDs) have emerged as pivotal nanomaterials for advanced electroluminescent displays, yet their efficiency remains constrained by limited triplet exciton utilization. Herein, we report a boron-nitrogen (B/N) co-doping strategy to engineer CDs with dual emissions of fluorescence and room-temperature phosphorescence, achieving high photoluminescence quantum yield (PLQY) of 86.41 %. The optimized blue carbon dot light-emitting diodes (CDLEDs) exhibit exceptional performance with a maximum luminance of 1,305 cd m⁻² and a groundbreaking external quantum efficiency (EQE) of 6.98 %, surpassing the 5 % theoretical limit for fluorescent systems. Theoretical analyses elucidate that B/N co-doping establishes a robust electron donor–acceptor framework, which enhances spin–orbit coupling, thereby synergistically facilitating reverse intersystem crossing and triplet exciton utilization. Furthermore, integration of these CDs with phosphorescent emitters yields warm-white LEDs with a luminance of 20,120 cd m⁻² and EQE of 3.69 %, setting new records for solution-processed CDLEDs in terms of brightness and efficiency. This work provides a dual-path exciton management paradigm, combining intrinsic triplet utilization and energy transfer engineering, paving the way for eco-friendly, high-performance electroluminescent technologies. © 2025 Elsevier B.V