IMPROVEMENT IN QUANTUM YIELD OF VARIOUS QUANTUM DOTS AND THEIR APPLICATION IN QUANTUM DOT LEDs

Abstract

The organic LEDs and Quantum dot LEDs can be a better solution that meets both the requirements i.e. Energy efficiency and durability of lighting sources. Quantum dot LEDs are one step ahead from organic light emitting diodes as they can use same quantum dot material to act as emissive layer, for any color combination. In this work fabrication and characterization of the quantum dot light emitting devices (QDLEDs) are carried out. In progress of that firstly quantum dots of different kinds have been synthesized, characterized and treated specifically to improve the quantum yield (QY). For CdSe quantum dots it was improved from 1.52 % to 16.03% while for CdS/CdZnS quantum dots it was increased from 12% to 45%. Characterization of quantum dots includes absorbance measurement, photoluminescence measurement, X-ray diffraction (XRD) analysis, X-ray photoelectron spectroscopy (XPS). Further fabrication of organic light emitting devices (OLEDs) was optimized. This optimized result was used in fabrication of quantum dot light emitting devices (QDLEDs).The blue color CdS/CdZnS quantum dots with 45% quantum yield was use as emissive layer. The electroluminescence of the device closely resembles with the spectra of warm white light.