White Light Emitting CdS Quantum Dot Devices Coated with Layers of Graphene Carbon Quantum Dots

Abstract

Cadmium sulfide quantum dots (CdS QDs) are semiconductor nanoparticles having sizes in the order of nanometers. They are materials that have outstanding properties for down conversion applications. These nanostructures have been used in the fabrication of white light emitting diodes (WLEDs) in the last years. However, inhomogeneous deposition of CdS QD conversion materials allows unwanted UV light escape. In addition, low efficiency due to strong self-quenching effect, incompatibility between CdS QD solution/crystal polyester resin matrix and reabsorption are common problems that need to be solved. In this work, we try to address the incompatibility between the CdS QD solution/crystal polyester resin matrix by using a solvent exchange procedure. To block the unwanted UV-light escape, we coated our devices with a mixture of graphene carbon quantum dot (GCQD) solution/crystal polyester resin matrix. The QDs and the WLED prototypes were characterized by absorption and photoluminescence (PL) spectroscopy. The QDs embedded in the matrix shown a good homogeneous dispersion. On the other hand, the mixture shown a rapid solidification. These facts indicate a good compatibility between the CdS QDs and the crystal polyester resin. We also observed a considerable reduction of unwanted near UV-light. White light emission from WLED devices with common crystal polyester resin and low-cost materials has been achieved.

Caracterización óptica y estructural de puntos cuánticos de carbono a base de tomate (lycopersicon esculentum Mill)

“…Los puntos cuánticos de carbono (CQDs: del inglés Carbon Quantum Dots) son conocidos por sus propiedades únicas, como su excelente emisión de luz, foto-estabilidad, biocompatibilidad, solubilidad en agua, absorción y emisión sintonizable, y baja toxicidad. Estas características hacen que los CQDs sean muy buenos candidatos para aplicaciones fotovoltaicas, iluminación, biodetección, liberación de fármacos, y catálisis, entre otras aplicaciones de interés (Cuadra et al, 2018;Deodanes et al, 2020;Liu et al, 2017;Sharma et al, 2019). Cuadra et al (2018) reportaron dos bandas de absorción, con máximos centrados alrededor de 230 nm y 350 nm para este tipo de nanoestructuras.…”

Dual-function perovskite light-emitting/sensing devices for optical interactive display

“…Since the first report of quantum dot light-emitting diodes (QLEDs) in 1994 3 , all kinds of quantum dots (QDs) candidate materials, including CdS [4][5][6] , CdSe [7][8][9][10] , InP [11][12][13] , etc., have been reported as potential luminescent materials for QLEDs. However, these QDs require a complicated core-shell synthesizing process, inert gas environment, and high synthesizing temperature [14][15][16][17] , posing a challenge for large-scale industrialization.…”