Design for White Light Emitting CdS Quantum Dots Devices Enhanced by Silver Nanoparticles

Semiconductor quantum dots have unique optical properties due to the quantum size effect and surface effect. Investigations of SPR effects on light-emitting materials and devices have increased in this decade because of their promising applications in the enhancement of the luminescence efficiency，which has demonstrated a good application prospect in the materials science, biomedicine, optoelectronic devices and other fields. In our work, we prepare trap-rich CdS nanocrystals in the oleic system, and prepare Ag nanoparticles with light induced, then combine them into four kinds of composite samples to investigate the phenomenon that Ag nanoparticles always quench the band-edge emission and enhance the surface-state emission regardless of the SPR wavelength. Experimental results show that we can change the color of?quantum?dots fluorescence because the proportion of the band-edge emission and the surface-state emission can be controlled by the distance between CdS quantum dots and silver nanoparticles. Then a white light Emitting CdS quantum dots devices enhanced by silver nanoparticles is designed using nine 395 - nm wavelength violet-LEDs as excitation?light?source, CdS quantum dots/silver nanoparticles samples and tinfoil which can block the extra light. From the picture of real products, it shows that Ag nanoparticles can change the color of?quantum?dots fluorescence and enhance the photoluminescence which will become stronger when CdS quantum dots and Ag nanoparticles come closer. This investigation not only provides a new approach to study the interaction between fluorescent?material and metal, but also discuss the devices promising application in color-changed luminescent?materials.