Trace Dual-Crosslinkable Additives Enable Direct Microlithography for Enhanced Organic Electrochemical Transistors

Similar to silicon-based electronics, the implementation of micro/nano-patterning to facilitate complex device architectures and high-density integration is crucial to the development of organic electronics. Among various patterning techniques, direct microlithography (DML) is highly applicable and extensively adopted in organic electronics, such as organic electrochemical transistors (OECTs). However, conventional DML often requires high crosslinker concentrations, leading to compromised electrical performance. To address this challenge, a novel strategy is developed that combines supramolecular and covalent interactions by incorporating a polyrotaxane supramolecular crosslinker (PR) into poly(benzodifurandione) (PBFDO). The PR forms a hydrogen bonding network with PBFDO and undergoes UV-triggered covalent crosslinking among its molecules, providing solvent resistance even at trace loading levels (<0.1 wt%). This approach enables precise patterning of PBFDO with feature sizes below 1 µm while preserving high electrical performance. Notably, PR also serves as a performance enhancer, promoting molecular ordering and ionic conduction within PBFDO. OECTs fabricated with PR-crosslinked PBFDO exhibit about one-order-of-magnitude increase in ON/OFF ratio, a 42% increase in µC^* (reaching 2460 F cm^-1 V^-1 s^-1), and elevated operational stability compared to pristine ones. This multifunctional crosslinker offers a scalable solution for high-performance, high-density organic electronics and opens new avenues for supramolecular chemistry applications in this field.