This study reports the synthesis and properties (in particular, the electrical switching characteristics) of a new high-performance polyimide (PI), poly(3,3'-di(4-(diphenylamino)benzylidenyliminoethoxy)-4,4'-biphenylene hexafluoroisopropylidenediphthalimide) (6F-HAB-TPAIE PI). This PI polymer bears diphenylaminobenzylidenylimine moieties as side groups and is dimensionally stable up to 280 degrees C and thermally stable up to 440 degrees C. In devices fabricated with the PI polymer as an active memory layer, the active PI polymer was found to operate at less than +/-2 V in electrically bistable unipolar and bipolar switching modes by controlling the compliance current. The PI polymer layer exhibits repeatable writing-reading-erasing capability with high reliability in ambient air conditions as well as at high temperatures up to 130 degrees C. This PI polymer also exhibits a high ON/OFF current ratio up to 10(9). The observed nonvolatile memory behaviors are due to Schottky emission and local filament formation. This study has demonstrated that this thermally, dimensionally stable PI polymer is a promising material for mass production at low cost for high-performance, programmable, nonvolatile memory devices that can be operated with low power consumption in unipolar and bipolar switching modes.

A novel polymer, poly(2-(N -carbazolyl)ethyl methacrylate) end-capped with fullerene (PCzMA-C(60) ), has been synthesized via living anionic polymerization. Electrically programmable flash memory devices were easily fabricated with this polymer by using solution coating and metal deposition. This polymer was found in these devices to exhibit bipolar and unipolar switching behaviors with a high ON/OFF current ratio, a long retention time, high reliability, and low power consumption. The excellent properties and easy processability of this polymer open up the possibility of the mass production of high performance nonvolatile memory devices at low cost.

The fully π-conjugated donor-acceptor hybrid polymers Fl-TPA, Fl-TPA-TCNE, and Fl-TPA-TCNQ, which are composed of fluorene (Fl), triphenylamine (TPA), dimethylphenylamine, alkyne, alkyne-tetracyanoethylene (TCNE) adduct, and alkyne-7,7,8,8-tetracyanoquinodimethane (TCNQ) adduct, were synthesized. These polymers are completely amorphous in the solid film state and thermally stable up to 291-409 °C. Their molecular orbital levels and band gaps vary with their compositions. The TCNE and TCNQ units, despite their electron-acceptor characteristics, were found to enhance the π-conjugation lengths of Fl-TPA-TCNE and Fl-TPA-TCNQ (i.e., to produce red shifts in their absorption spectra and significant reductions in their band gaps). These changes are reflected in the electrical digital memory behavior of the polymers. Moreover, the TCNE and TCNQ units were found to diversify the digital memory modes and to widen the active polymer layer thickness window. In devices with aluminum top and bottom electrodes, the Fl-TPA polymer exhibits stable unipolar permanent memory behavior with high reliability. The Fl-TPA-TCNE and Fl-TPA-TCNQ devices exhibit stable unipolar permanent memory behavior as well as dynamic random access memory behavior with excellent reliability. These polymer devices were found to operate by either hole injection or hole injection along with electron injection, depending on the polymer composition. Overall, this study demonstrated that the incorporation of π-conjugated cyano moieties, which control both the π-conjugation length and electron-accepting power, is a sound approach for the design and synthesis of high-performance digital memory polymers. The TCNE and TCNQ polymers synthesized in this study are highly suitable active materials for the low-cost mass production of high-performance, polarity-free, programmable, volatile, and permanent memory devices that can be operated with very low power consumption, high ON/OFF current ratios, and high reliability.