High efficient light-emitting diodes based on liquid-type carbon dots

Abstract

Carbon dots (CDs) are considered as potential luminescent sources in light-emitting devices but CDs in the dry and solid aggregate state have strong luminescence quenching. Here we report monochromatic light-emitting diodes originating from the carbon dots in liquid format. The CDs were stored in a glass box and packaged with a UV-LED chip. These devices emitted stable luminescence colors ranging from blue to red, which were determined by the concentration of CDs in toluene. The maximum luminous efficiency was 2.27 times higher than that of solid devices. We further fabricated liquid type white light-emitting diodes with blue emissive CDs and green and red emissive colloidal semiconductor quantum dots which showed a high color rendering index (CRI) of 91 and a good stability.