The Polymer Society of Korea

Abstract

Charge transport in polymer OFETs is strongly governed by thin-film microstructure, particularly nanoscale morphology and crystalline orientation established during film formation. Polar poor-solvent engineering was applied to an alkyl-substituted NDI–BTBT polymer to induce microphase separation and improve charge-transport pathways. The addition of a methanol to a chlorobenzene-based solution led to the formation of nanowire-like aggregates, resulting in a pronounced mobility enhancement from 2×10⁻⁵ to 4×10⁻³ cm² V⁻¹ s⁻¹. To assess the role of solvent polarity, DMF (polar) and hexane (nonpolar) were compared, and an optimal methanol content of 10 vol % was identified. GIWAXS and AFM analyses corroborated enhanced edge-on ordering/crystallinity and nanowire morphology, supporting a clear structure–property correlation in which polar poor-solvent-induced structural organization translates into improved charge transport.