High-κ polymers of intrinsic microporosity: a new class of high temperature and low loss dielectrics for printed electronics†
High performance polymer dielectrics are a key component for printed electronics. In this work, organo-soluble polymers of intrinsic microporosity (PIMs) are reported for the first time to demonstrate desirable dielectric properties with a high permittivity (or κ), heat resistance, and low dielectric loss simultaneously. Due to the highly dipolar sulfonyl side groups (4.5 D) and rigid contorted polymer backbone, a sulfonylated PIM (SO2-PIM) enabled friction-free rotation of sulfonyl dipoles in the nanopores. As such, an optimal balance between relatively high κ and low dielectric loss is achieved in a broad temperature window (−50–200 °C). For example, the discharged energy density reached 17 J cm−3 with κ = 6.0. The discharge efficiency was 94% at 150 °C/300 MV m−1 and 88% at 200 °C/200 MV m−1. Furthermore, its application as a high-κ gate dielectric in field effect transistors (FETs) is demonstrated. With the bilayer SO2-PIM/SiO2 gate dielectric, InSe FETs exhibited a high electron mobility in the range of 200–400 cm2 V−1 s−1, as compared to 40 cm2 V−1 s−1 for the bare SiO2-gated InSe FET. This study indicates that highly dipolar PIMs with a rigid polymer backbone and large free volume are promising as next generation gate dielectric materials for printed electronics.