(181j) Optical and Electrical Properties of Solution-Mixed and Sequentially Processed Poly(3-alkylthiophene):F4TCNQ Films | AIChE

(181j) Optical and Electrical Properties of Solution-Mixed and Sequentially Processed Poly(3-alkylthiophene):F4TCNQ Films

Authors 

Fergerson, A. - Presenter, University of California, Davis
Bedolla-Valdez, Z. I., University of California, Davis
Raza, Z., University of California, Davis
Guo, J., University of California, Davis
Moulé, A. J., University of California, Davis
Ayala-Oviedo, A. N., University of California, Davis
Portillo, A. A., University of California, Davis
Substantial research has been conducted on the optical and electrical properties of poly(3-alkylthiophene) (P3AT) thin films deposited using a range of solvents. Recent work from our group compared the effects of doping P3HT films with F4TCNQ using a mixed-solution method and sequential processing method using an orthogonal solvent. Films processed sequentially exhibit higher conductivities than those doped using a mixed-solution method. Furthermore, we showed that the choice of sequential doping solvent controls whether or not dopant anions are inserted into crystalline domains within the solid polymer matrix. We can rationalize these results by using a Langmuir isotherm model and accounting for the accessibility of doping sites in amorphous vs crystalline domains. Here, we generalize these conclusions about sequential doping methods using other P3ATs that have a different ratio of crystalline to amorphous domains. Using UV-Vis spectroscopy, we show that it is possible to control the doping level of P3AT films by varying the concentration of the sequential dopant solution. Four-bar conductivity measurements confirm that sequentially doped P3ATs generally exhibit higher conductivities than mixed-solution processed films at the same doping level. These trends demonstrate that the optical and electrical advantages of the sequential doping process are not limited to P3HT films and that the Langmuir isotherm model provides an appealing link between electrical properties and thermodynamics.

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