EXAMINING CHARGE CARRIER TRAPPING AND RECOMBINATION IN ORGANIC PHOTOVOLTAICS

Open Access
Author:
Banyas, Kyle Mark
Graduate Program:
Chemistry
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
March 23, 2011
Committee Members:
  • John B Asbury, Thesis Advisor
  • John V Badding, Thesis Advisor
  • Mark Maroncelli, Thesis Advisor
Keywords:
  • CHARGE CARRIER RECOMBINATION
  • CHARGE CARRIER TRAPPING
  • ORGANIC PHOTOVOLTAICS
Abstract:
The energy consumption of the planet is currently very high and expensive. With developing nations such as India and China increasing their need for energy, it has moved the energy issue to a front line topic. The high cost of energy has started to hit home to many people with the recent increase in the cost of fossil fuels, specifically gasoline. Gas prices have been steadily on the rise for the last decade. Recently the environmental repercussions of the use of fossil fuels have been headlined in the media. From the oil rig disaster in the Gulf of Mexico to the mine collapses across the world the danger of going after these natural resources has become evident. Global warming has also become an issue not only in the scientific community but also in the political. With these factors in mind a search for a renewable source of energy has begun in earnest. Renewable energy sources could help alleviate the worlds thirst for energy and reduce the emissions that contribute to global warming. Solar technology has been lauded as one of the renewable energy sources that has the most promise to contribute to the current energy crisis. Solar energy has the potential to produce all the energy the world needs, however there are many issues to overcome. Inorganic, primarily silicon, solar cells have been in use for decades at this time but are too expensive to effect the global market. A current area of research interest is in the area of organic photovoltaics (OPVs). OPVs show promise to have a lower cost than inorganic solar cells, however they currently suffer from very low efficiencies and lifetimes. Current OPVs have too low efficiencies in order to be integrated into the energy production methods. Research is being done in order to improve solar technologies in hopes to provide a significant amount of energy for the world. Two of the issues involved in OPVs are charge carrier mobility and recombination. This study focuses on these two issues using two complementary experiments. First being the Charge Carrier Extraction by Linear Increasing Voltage (CELIV) experiment that allows for the determination of the mobile charge carriers present in the sample. The complementary spectroscopic technique is a visible pump infrared probe transient experiment that allows for the determination of all the charge carriers present with a sample. By examining these two techniques information can be drawn about the charge trapping that takes place with the system. Understanding these issues are the first steps to overcoming them and bring forth OPVs as a viable energy source.