We investigate the chemical and structural properties of solution-processed thin films of P3HT blended with p-type dopant F4TCNQ. The maximum in-plane electrical conductivity of doped films is observed at a molar doping fraction of 0.17, in agreement with the binding mechanism of F4TCNQ:P3HT complexes. Through the use of X-ray diffraction, a previously unreported crystalline phase is observed for P3HT films doped above a critical threshold concentration. This crystalline phase involves the incorporation of F4TCNQ molecules into ordered polymer regions and ultimately improves charge dissociation, leading to higher carrier density in thin film. Finally, optical absorption and X-ray diffraction reveal that the chemical state of P3HT in solution has a dramatic impact on the electrical and structural properties of the blended films.Graphical abstract
Highlights► We study the p-type doping of P3HT with optical absorption and X-ray diffraction. ► F4TCNQ forms charged complexes with P3HT in solution above a certain concentration. ► We reveal a previously unreported crystalline phase in F4TCNQ doped P3HT films. ► Chemical state of P3HT in solution impacts thin film properties. ► Maximum film conductivity of 1.8 S/Cm is observed at ∼17% dopant concentration.
