Document Type

Dissertation - University Access Only

Award Date

2012

Degree Name

Doctor of Philosophy (PhD)

Department / School

Electrical Engineering and Computer Science

First Advisor

Qiquan Qiao

Abstract

Photovoltaics is a renewable energy technology that has drawn worldwide attention due to increasing demands of energy. However, production costs of silicon solar cells remain very high. Conjugated polymer based solar cell is a promising alternative photovoltaic technology, due to solution-based processing and reduced material cost. Previous work on polymer/inorganic semiconductor hybrid solar cells showed efficiency around 3%, which is still far below polymer/fullerene based cells. There is a strong need for environmentally clean, easily processed organic-inorganic systems for efficient and cost effective organic-inorganic solar cells. The goal of this dissertation was to develop cost effective and easily processed organic-inorganic hybrid system for solar cells and to increase cell efficiency. The objectives were to develop nanostructure inorganic semiconductors as acceptors, low bandgap conjugated polymers as donors; investigate charge transfer mechanism in donoracceptor composite; develop simple processed organic-inorganic hybrid solar cells with an in-situ fabrication strategy to assemble donor and acceptor; acquire an understanding of organic-inorganic solar cells operation mechanism; and develop cost-effective hybrid solar cells having an efficiency of at least 5 % using costeffective materials. P3HT/Ti02 nanocomposites made by chemically linked method was prepared and characterized. UV -Visible absorption, steady state fluorescence emission (FL) and femtosecond up-conversion fluorescence system (FFU) methods were applied to investigate energy migration and charge transfer dynamics. ZnO nanostructure films with nano-ridges and nanorods morphologies were prepared and characterized. P3HT/ZnO bilayer and ordered heterojunction solar cells were fabricated and characterized by current density versus voltage (JV) and external quantum efficiency (EQE) measurements. In situ electrochemical polymerization of polymers into nanostructure materials were investigated. ZnO nanorods/P3HT device was made with an efficiency of 0.31 %, which is comparable to the literature. Future work should include fabricating efficient ZnO nanostructured hybrid solar cells by combining it with low bandgap polymers, and electrochemically grown novel low bandgap polymers into nanostructure inorganic semiconductor systems.

Library of Congress Subject Headings

Nanostructured materials
Solar cells
Photovoltaic power generation -- Economic aspects

Publisher

South Dakota State University

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Rights Statement

In Copyright