The combined effect of intercalated oxidant and thermal annealing on surface morphology and photo-physical properties of poly(3-octylthiophene) films

As intercalated oxidant (guest) is chemically de-intercalated stepwise from poly(3-octylthiophene) (P3OT) (host), a gradual evolution of a mat-type crystalline structure is observed. Moreover, the intercalated oxidant has marked effect on the arrangement of polymeric chains. Complete thermal de-intercalation of oxidant leads to interwoven cylindrical bundles of polymeric chains similar to corrugated-rod-type (CRT) morphology seen for thermally annealed pristine P3OT. The red shift along with increase in intensity and sharpness in UV–vis spectra and photoluminescence quenching indicate that the ripening of the self-assembling nature of pristine P3OT polymer leads to the formation of polymeric quasi-crystals when it is freed from oxidant impurity chemically or by prolonged soft-thermal annealing of oxidant intercalated polymer matrix. The present results enable the analysis of the effects of geometrical parameters characterizing the mutual host–guest complementarity as well as host–guest and guest–guest interactions on the crystal packing of intercalate.