A Study of Charge Mobilities in Annealed Poly(3-hexylthiophene-2,5-diyl) Thin Film Transistors and Optimization of Zone Annealing

Open Access
Author:
Thomas, Seth
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
  • polymers
  • zone annealing
  • zone
  • annealing
  • transistor
  • transistors
  • TFT
  • OFET
Abstract:
Polythiophene thin film devices are promising sources of next generation organic electronics that may one day be implemented into industry as well as common household items. We have analyzed the charge mobility of poly(3-hexylthiophene-2,5-diyl) (P3HT) thin-film transistors (TFTs) under conditions of altered recrystallization kinetics. Charge mobility increases in regions of higher order in polythiophenes as a consequence of greater density of tie molecules. Our results suggest that controlling recrystallization kinetics and ultimately the number of higher ordered regions in P3HT, namely by increasing both quenching temperature and time, might result in increased charge mobility in polythiophene thin films. Our results also suggest that as TFTs degrade due to prolonged exposure to non-inert and non-vacuum environments charge mobility also decreases, characterizing the delicate nature of polythiophene thin films. We have also analyzed the ability of zone annealing to enhance the UV absorbance and ultimately the density of ordered regions in P3HT thin films. Zone annealing allows for control of recrystallization kinetics over the thin film to a much higher degree than traditional hot plate annealing. We have found the optimal speed and cooling block spacing settings for the custom fabricated linear zone annealing apparatus to vary with temperature gradient based on heat source temperature. Future work with the zone annealing apparatus may utilize these results to alter the crystallization of thin films for transistor applications.