π-Conjugation-interrupted hyperbranched polymer electrets for organic nonvolatile transistor memory devices

By means of the limited conjugation length, the intrinsic 3-dimensional conformations and the potential nanoporous structures, pi-conjugation-interrupted hyperbranched polymers (CIHPs) were demonstrated as polymer electrets for the application of organic transistor memory devices. As models of CIHPs, PPF and PPF8 were synthesized via Friedel-Crafts C-H polymerization for investigation of the structure-performance relationship according to four-element theory. They exhibited good solubility in organic solvents, excellent thermal stability and film-forming ability. The preliminary as-fabricated transistors showed memory effects with large hysteresis windows and reliable programming/erasing cycles. Furthermore, devices based on PPF exhibited higher mobility, larger ON/OFF ratio and better data retention capability than those based on PPF8. The negative effect of the substitution of alkoxyl groups on the device performance suggests that charge trapping and storage are highly sensitive with electrets' molecular orbital energy levels, vibration relaxation mode, chain aggregates, and surface energy. Soluble organic framework polymers will be potential advanced organic nanomaterials for plastic electronics and mechatronics.