Investigating vapor doping dynamics in poly(3-alkylthiophenes) using <i>in situ </i>technique

For conjugated polymers to be utilized in future organic electronic technology, their conductivity must be able to be controlled. Molecular doping has been used for this purpose, but details of this process are not well understood. Here, we report on a study of vapor doped poly(3-alkylthiophenes), a conjugated-polymer system that has been widely characterized. We use traditional dopant 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane and its less fluorinated cousins, along with poly(3-alkylthiophenes) with varying sidechain length, to probe how HOMO-LUMO overlap and spacing of the polymer affects the dynamics of the vapor doping process. These results are enhanced with characterization of the materials energetically and structurally at various time-points throughout the doping process. Spectroscopies such as UV-Vis, FTIR, and Raman give insight to the efficiency and mechanism of doping. This study shows how these techniques can be leveraged to probe how variables such as polymer structure, strength of dopant, and processing affect the final properties of molecularly-doped conjugated polymers.