Temperature resistant amorphous polyimides with high intrinsic permittivity for electronic applications

Abstract

High–dielectric–constant (high–k) polymers are highly desirable for high energy density capacitors and low–voltage organic thin-film transistors (OTFTs). However, conventional high–k polymers suffer from low temperature resistance or crystalline state, hampering their applications in electronic devices in general environments. Herein, by accurate monomer design and mild polycondensation, we synthesize a new polyimide (STP–PI) featuring amorphous state, intrinsic high–k, very high thermal stability, and self-standing properties. Having polar side groups and rigid twisty backbones, the STP–PI exhibits both high and stable permittivity (5.2 ∼ 6.0 from 1 MHz to 100 Hz) and excellent thermal stability (Td5% > 450 °C and Tg > 300 °C), superior to its counterpart without the polar side group. When applied for energy storage, STP–PI delivers a discharged energy density of 3.68 J cm−3 with discharge efficiency of 84% at 350 MV m−1 even at 200 °C, which makes a record among the state–of–the–art performance of instinct polymer dielectrics. When applied in low-voltage OTFTs as the dielectric layers, the devices show a low threshold voltage of −0.30 V and mobility value of 4.03 cm2 V−1 s−1. The design strategy paves a way of making high–k polyimides for high temperature energy storage and electronic applications.