Boosting OECT performance with PEGylated gold nanoparticles in hydrophobic channels

Organic electrochemical transistors (OECTs) require organic mixed ion-electron conductors (OMIECs) (i.e., hydrophilic materials supporting electron and ion transportation) as active materials. However, high-performance OMIECs grafted with hydrophilic side chains are difficult to synthesize and purify, and often suffer from swelling during operation. In contrast, the synthetic pathways toward a broad range of hydrophobic polymeric semiconductors used in classic organic-field-effect transistors are well established, and several are even commercially available. Yet, these hydrophobic materials do not intrinsically support ionic transport, limiting their application in OECTs. Here, poly(ethyleneglycol) (PEG)-coated gold nanoparticles (AuNP) are incorporated into conventional hydrophobic polymeric semiconductors like poly-3-hexylthiophene (P3HT), improving not only ionic but also electronic transport. The hydrophilic AuNPs modify P3HT crystallite orientation, shorten lamellar and π–π distances, and create pathways for ion penetration, as evidenced by GIWAXS and AFM studies. With 5 wt% AuNP loading, OECTs achieve µC* of 98 F cm−1 V−1 s−1, comparable to hydrophilic materials. The strategy also works for other polymer systems, offering a facile method to utilize hydrophobic materials in OECTs and boost their performance.