Ultrahigh Brightness Carbon Dot-Based Blue Electroluminescent LEDs by Host-Guest Energy Transfer Emission Mechanism

Ultrahigh brightness blue carbon dot-based light-emitting diodes (CD-LEDs) are fabricated by a host-guest doping method with poly(N-vinylcarbazole) (PVK) as the host to realize the high brightness and pure emission of CD-LEDs. Oleophylic CDs are synthesized as the dopant to obtain a wide range of doping concentration of CDs because oleophylic CDs and PVK can be well cosoluble in chlorobenzene at any doping concentration. Therefore, the CD-LEDs emitting pure blue light that dominantly originates from CDs' emission are realized by optimizing the doping concentration. A host-guest energy transfer is the main emission mechanism for CDs. It is observed that CD-LED also achieves a maximum luminance of 569.8 cd m(-2), which is the highest luminance compared with ever reported blue CD-LEDs.