Dr. Shawna Ellis is an Assistant Professor of Organic Chemistry in the Chemistry & Physics Department at Southwestern Oklahoma State University (SWOSU).
EDUCATION
2005 – B.S. Chemistry, University of Oklahoma
2012 – M.S. Organic Chemistry, University of Oklahoma
2013 – Ph.D. Organic Chemistry, University of Oklahoma
2024 – Began teaching at SWOSU
RESEARCH
Design and Synthesis of an Organic/Inorganic Dye that is Protected from Photo-Oxidation
Dr. Shawna Ellis (Mentor)
Actively accepting research students for credit.
Background and Significance. Inspired by nature, dye-sensitized solar cells (DSSCs) have the potential to be a powerful source of renewable energy in the coming years. DSSCs mimic the process of photosynthesis, but instead of using chlorophyll pigments to harvest light in order to produce biochemical energy, light is harvested by manmade fluorescent dyes and converted into electricity. The appeal of DSSC lies in the opportunities for the cheap construction of these systems and their subsequent mass production. However, current versions have low efficiency compared to silicon solar cells, as well as low durability therefore the practical application of these cells has not become widespread. Therefore an important target area for improvement of solar cells and photovoltaic devices is the development of cheaper, environmentally friendly, more redox stable dyes which will therefore increase electron injection. Most importantly, the target dye system should have a limited ability to aggregate, which will prevent the system from breaking down over time due to photo-oxidation.
This research proposes to stabilize the radical dication of the excited dye by strategic supramolecular interaction, such as the use of a molecular cage to encapsulate the dye, thereby creating a stabilizing environment around the excited dye leading to increased fluorescence, reducing the recombination of the excited electron with the dye. This method would have the added benefit of preventing the dyes from aggregating with other dyes in their cationic states, which leads to an undesirable electron transfer which destroys the dye through the irreversible process of photo-oxidation.
Research Plan. This project will be to study host guest systems as possible candidates for use in dye-sensitized solar cells. Specifically, cucurbit[n]urils (CB[n]) will be studied in combination with commercially available Rhodamine and Pyronin organic dyes, as well as Ru-based inorganic dyes. The encapsulation of these dyes with CB[n] results in the formation of strong intramolecular interactions between host and cationic guest, which is envisioned to modify the photo-chemical properties of the dye. In addition, CB[n] is expected to increase the durability and overall lifetime of the cell by protecting the dye from aggregating with neighboring substances leading to undesirable electron transfer and photo-degradation.
These properties will be tested in bulk solution by cyclic voltammetry experiments using a potentiostat, and Indium Tin Oxide (ITO) as the conducting electrode as is used commonly in DSSCs. The redox properties of the dyes in the presence and absence of CB[n] for application in DSSC will be evaluated in order to assess the encapsulating molecule’s ability to provide stability to the excited state to and to protect against photo-oxidation. If successful, a DSSC would be constructed using established methods in the literature and the current and voltage would be measured. Based on previous work, it is expected that the encapsulation will reduce the ability of the dye to bind to ITO, necessitating synthetic work to achieve surface attachment of the dye or CB[n] or both. In particular, the Ru-based inorganic dyes and the cucurbit[n]urils are excellent targets for synthetic modification using Organic synthesis.
CONTACT INFORMATION
Email: shawna.ellis@swosu.edu Office Number: CPP 205-E
Phone Number: 580-774-3202
TEACHING: BASIC COURSES
CHEM 1203 Gen Chem
CHEM 1252 Gen Chem I Lab
TEACHING: ORGANIC CHEMISTRY
CHEM 3013/3015 Org Chem I
CHEM 3111/3015L Org Chem I Lab
CHEM 4113/4115 Org Chem II
CHEM 4021/4115L Org Chem II Lab
OTHER ACTIVITIES
AUGUST 2024 – PRESENT
Chemistry Club Sponsor
RECENT PUBLICATIONS
Shawna B. Ellis; Moore, Jillian; Cochran, Richard; Khadka, Usha; Nia, Oliver; Jacobs, Kyle; Halterman, Ronald L. Effects on Host‐Guest Complexation Between Cucurbit[7]uril and Sterically or Electronically Modified Benzyldipyridyl Derivatives. Tetrahedron Letters. 2023 (manuscript in preparation)
Bergagnini, Mackenzie; Howe, Mitchell; Ramirez, Dave; Welander, Ellen; Ellis, Shawna B.; Eitrheim, Eric; Ellis, Trevor K. Design, Synthesis, and Crystallographic Analysis of a Novel Set of Ni(II) Complexed Nucleophilic Glycine Complexes. 2023 Journal TBD. (manuscript in preparation)
Bergagnini, Mackenzie; Howe, Michell; Burgess, Emily; Wright, Payton; Hamburger, Samantha; Zhong, Zhennan; Ellis, Shawna; Ellis, Trevor. Synthesis of trifluoromethyl substituted nucleophilic glycine equivalents and the investigation of their potential for the preparation of a-amino acids. Tetrahedron, 2021, 77, 131741.
Figueroa, Luis E.; Brown, Megan C.; Briscoe, Thomas; Chisam, Juliette; Lewis, Dalton; Westover, Justin; Brooks Erin; Albahadily,Fakhrildeen; Bowen, John; Ellis, Shawna B. 2019 Synthesis of a potential new internal standard for the analytical determination of dibutyl phthalate (DBP) and monobutyl phthalate (MBP) in water samples. Proceedings of the Oklahoma Academy of Science. 2019.
Ellis, Shawna B.; Khadka, Usha K. Computational and experimental studies of new cucurbit[n]uril containing building blocks. National Meeting of the American Chemical Society, Orlando, FL. 2019
Ellis, Tanara; Ellis, Shawna B.; Ellis, Trevor K. Development of a Green Laboratory Experiment for Organic Chemistry II Students. National Meeting of the American Chemical Society, New Orleans, LA. 2018.
