Conjugation-Break Spacers in Semiconducting Polymers: Impact on Polymer Processability and Charge Transport Properties

Conjugation-break spacers (CBSs) are intentionally introduced into the diketopyrrolopyrrole (DPP)-based polymer backbones. We reveal that the solution processability progressively increases with the percentage of CBSs, while charge mobility inversely varies to the CBS ratio. For instance, the polymer DPP-30 with solubility of ∼10 mg/mL in dichlorobenzene provides an average mobility over 1.4 cm2 V–1 s–1, while DPP-0 exhibits an average mobility of 4.3 cm2 V–1 s–1 with solubility of ∼3 mg/mL. This correlation provides a general guidance to design polymers with desired electronic performance and solution processability for large-scale roll-to-roll processing. Most encouraging, DPP-70 can be melt processed in air and provide hole mobilities up to 0.30 cm2 V–1 s–1, substantially higher value than their solution-processed counterparts about 0.1 cm2 V–1 s–1. The mobility boost in melt-processed devices, together with completely eliminating the need to use toxic solvent in the processing, encourages to design melt-processable polymers for electronic devices.