Highly stable and bright blue light-emitting diodes based on carbon dots with a chemically inert surface

Abstract

The manufacture of blue light-emitting diodes (LEDs) has always been a tough problem to solve in the display and illumination fields. Inorganic/organic semiconductors and carbon dots (CDs) with a wide band gap still face obstacles such as a low external quantum efficiency (EQE) and poor stability. Herein, we synthesized highly stable and blue emission CDs with a chemically inert surface, and the photoluminescence (PL) peak (in ultra-pure water) of which is located at 446 nm with an absolute PL quantum yield (PLQY) of 26.4%. The LEDs based blue emission CDs exhibit an electroluminescence (EL) peak located at 456 nm and a high brightness of 223 cd m⁻² with an EQE of 0.856%. The Commission Internationale del'Eclairage (CIE) coordinates are located at (0.21, 0.23) and the device lifetime with 65% brightness (T₆₅) reaches over 217 h because of the chemically inert surface of the CDs. The results mean the devices are the most stable CDs-LEDs reported to date. This work represents a novel route for the preparation of low cost, highly stable and very bright CDs-LEDs with a short wavelength emission.