GEORGIA INSTITUTE OF TECHNOLOGY

Under the provisions of the regulations for the degree

DOCTOR OF PHILOSOPHY

on Thursday, June 27, 2019

10:00 AM
in MoSE 3201A

will be held the

DISSERTATION DEFENSE

for

Jing Zhou

"Modulated Optical Behavior of Nanostructured Electrochromic Conjugated Polymer Hybrids"

Committee Members:

Prof. Vladimir V. Tsukruk, Advisor, MSE

Prof. John R. Reynolds, Chem/MSE

Prof. Zhiqun Lin, MSE

Prof. Dong Qin, MSE

Prof. Valeria Milam, MSE

Abstract:

Noble metal nanoparticles and semiconducting quantum dots are promising building blocks for tailoring light-matter interactions at the nanoscale, which find applications in miniaturization of photonic devices, high-throughput optical sensing, and super-resolution imaging.  While the optical properties of these inorganic nanoparticles alone have been largely understood, active control of their optical behavior with external fields remains challenging.  This dissertation aims to understand and develop novel nanostructured electrochromic conjugated polymer (ECP)/optical inorganic nanoparticle hybrids with electrochemically modulated extinction of noble metal nanoparticles and photoluminescence of semiconducting quantum dots.  Important focuses are placed on developing synthetic strategies to fabricate ECP-inorganic nanoparticle hybrids and understanding their optical response as affected by the interfacial assembly, spectral overlap, refractive properties and redox states of ECP during the in-situ electrochemical reaction. 

As a result of this study, the core-shell hybrid plasmonic nanostructures assembled from a gold nanoparticle core with a various of ECP shells were synthesized by in-situ chemical oxidative polymerization.  Different electrochemical plasmon tuning systems have been realized with these hybrids including a dual responsive system with reversible plasmonic shift reaching 150 nm and a system possessing an easily identifiable narrow visible-near infrared absorption band.  Next, a manyfold reversible increase in dark-field scattering intensity was revealed for the single hybrid nanoparticle when the conjugated polymer shell was electrochemically switched, which enables the real-time visualization of the redox reaction of conjugated polymer down to single nanoparticle level.  Last, by maximizing the spectral change in an ECP with emission of quantum dot in a nanostructured assembly, we demonstrate the electrochemical modulation of quantum dot photoluminescence with a remarkable optical contrast.  Overall, we suggest that unique modulated optical behavior that is unachievable in individual components can be accomplished through careful design of spectrally matched hybrid materials.  The knowledge obtained in this study can be used to improve the design of high-throughput optical sensors with enhanced sensitivity and scalable, flexible, high-performance displays.