Bright White Light Emission of Ultrasmall Nanocrystals for Use in Solid State Lighting
Harrell, Sarah-Ann Michelle
White light-emitting diodes (LEDs) are the lighting of the future due to their potential energy savings and the proven success with monochromatic LEDs. However, white LEDs require an expensive fabrication process involving the incorporation of many different monochromatic semiconductors into a single LED; this is often referred to as color mixing. In 2005, a new class of semiconductors was discovered which is called ultrasmall CdSe quantum dots. This new class of material emits perfect, white light, so the integration of ultrasmall CdSe quantum dots into LEDs would result in the eradication of all the costs associated with color mixing. Since its discovery, the brightness of ultrasmall CdSe nanocrystals has increased over time from a ~2% quantum yield to ~31 with a brightening method which has been termed the formic acid treatment. This thesis pertains to the improvement and LED amalgamation of these brighter ultrasmall CdSe quantum dots. In particular, many experiments were done with the goal of improving the formic acid treatment, and in the process, much was discovered about the mechanics of the brightening method. The last chapter of the thesis concludes about the results and gives possible future directions including characterization methods and another possible brightening method.