Quantum Characterization of Polymers of Interest for Application as Organic Photovoltaics

Open Access
Author:
Elledge, Grant Lord
Area of Honors:
Chemical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Enrique Daniel Gomez, Thesis Supervisor
  • Michael John Janik, Honors Advisor
Keywords:
  • P3HT
  • PBTTT
  • PFOTBT
  • PCBM
  • OPV
  • organic
  • photovoltaic
  • solar
  • torsion
  • torsional angle
  • torsional energy profile
Abstract:
The purpose of this research was to characterize the torsional properties of organic photovoltaics (OPVs), namely, P3HT, PBTTT, and PFOTBT. The energy as a function of the torsional angle along the bond connecting the backbone rings (e.g. thiophene rings, in the case of P3HT) was determined to quantify the likelihood of the polymer to break pi-orbital conjugation, a necessary electronic property for the target application of charge transfer along the polymer backbone. Gaussian 09 and Gaussview were used to perform quantum chemical calculations. Due to computational restrictions, a small oligomer model for each of the polymers represented the extended polymer. An alkane functionalization representing the side chains of these polymers of at least two carbons (ethyl functionalization) was determined to be the minimum number needed; fewer carbons were clearly not representative of the model. Increasing the number of monomers above the minimum number able to represent the system demonstrated that the minimum number able to represent the system did not model the larger polymer completely accurately.