Lithium Salt Doping of Organic Photovoltaics
Open Access
- Author:
- Williams, Bryan Paul
- Area of Honors:
- Chemical Engineering
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Dr. Enrique Daniel Gomez, Thesis Supervisor
Dr. Wayne Roger Curtis, Thesis Honors Advisor - Keywords:
- Solar
Photovoltaics
Williams
Gomez
Doping
organic
electronics
polymers - Abstract:
- Charge recombination and low charge mobility significantly hinders the performance of organic solar cells with thin active layers. In an effort to overcome these obstacles, lithium salt was added to a novel polymer, M-TQ1, blended with an electron acceptor, PCBM, in an attempt to increase dielectric permittivity and hole mobility, in order to improve organic photovoltaic (OPV) performance. This hypothesis was tested with organic field-effect transistors (TFT), TEM imaging, and performance of fabricated polymer solar cells. Lithium salt-doping was found to be an effective additive to increase both hole mobility and charge recombination lifetime. These experiments demonstrated increases of two orders of magnitude in hole mobility and almost an order of magnitude in recombination lifetime in the lithium-doped M-TQ1. However, these improvements did not translate seamlessly to enhancements in solar cell performance. Inadequacies in the morphology, namely phase separation, of PCBM/M-TQ1 solar cells prevented the majority of the excitons from reaching the blend interface, proving to be detrimental to device performance. If issues associated with the active layer morphology could be resolved, the improvements to electronic properties with lithium salt doping seen in TFT measurements could one day be translated to polymer solar cells, which could prove to be a revolutionary advance in our energy infrastructure.