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[Display omitted] • An intrinsic high– k polyimide with rigid backbone and polar side groups was reported. • STP-PI presented high permittivity (5.2 ∼ 6.0) and excellent thermal stability. • At 200 °C, STP-PI delivered a discharge energy density of 3.68 J cm-3. • The OTFTs based on STP–PI showed a low threshold voltage and high mobility value. 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 (T d5% > 450 °C and T g > 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. [ABSTRACT FROM AUTHOR]