Unravelling the mechanism of processing protocols induced microstructure evolution on polymer thermoelectric performance

Processing protocols definitely impact polymer microstructure evolution and thermoelectric (TE) perfor-mance; however, in-depth understanding of molecular mechanism is still a challenge. Here, the mecha-nism of the effects of solution-and melt-processing protocols on polymer microstructure evolution and TE performance has been unraveled, where a semicrystalline poly(3-hexylthiophene) (P3HT) is chosen as a model system. The phase separations between crystallites and amorphous regions are more pro-nounced for melt-processed films, and solution-processed films display enlarged conjugation length and higher degree of solid-state ordering. In crystalline domains, solution-processed films reveal a completely edge-on structure, while melt-processed exhibit a co-existing of edge-on and face-on crystallites. Addi-tionally, solution-aging strengthens aggregation and phase separation, but has little effect on conjugation length and crystalline texture. Finally, a multiphase semicrystalline model, based on crystalline texture and phase separation, is applied. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study revealed the mechanism of how solution-processed and melt-processed protocols affect the microstructure evolution and thermoelectric performance of polymer P3HT. Results showed significant differences in phase separations between crystallites and amorphous regions for the two processing methods, with solution processing leading to longer conjugation lengths and higher degrees of solid-state ordering.