Alloyed heterojunction nanorods and their applications
In the Shim research lab, we work to both synthesize novel nanomaterials and integrate them into electronic devices. The goal of my research was to improve the utility of our existing heterostructures in optoelectronic devices, and my main tool was alloying. The first half of my dissertation focuses on CdSe/CdTe heterojunction nanorods for use in photovoltaics. First, I utilized a simple post-synthesis ligand exchange procedure to greatly improve their environmental stability. Then, we integrated them into sensitized solar cells. By alloying CdTe with Se through a slow-injection procedure and by adopting a partial core/shell morphology, we were able to better balance light absorption with charge extraction and ultimately achieve solar cells with 5.9% power conversion efficiency. The latter half of my dissertation focuses on our group's flagship material, the double-heterojunction nanorod, which can outperform traditional quantum dots in red light-emitting diodes. I investigated methods to alloy the emitting material while maintaining proper energy band alignment in the heterostructure, with the goal of extending the emission range to green or even blue. I developed a new two-step cation exchange process to alloy the nanorods with Zn while preserving their shape. With subsequent shell growth, we can achieve single-peak photoluminescence spanning the entire visible spectrum (400 – 635 nm).
semiconductor, nanocrystal, led, solar cell
University of Illinois - Urbana-Champaign
Networked Digital Library of Theses and Dissertations
University of Illinois at Urbana-Champaign