Rewritable Resistive Memory Effect in poly[N-(3-(9H-carbazol-9-yl)propyl)-methacrylamide] Memristor

The synthesis of poly[N-(3-(9H-carbazol-9-yl)propyl)methacrylamide] (PCaPMA) is presented, along with its physical, photophysical, and electrical properties, revealing its promising potential for the application in bistable memory devices. The incorporation of the carbazole heterocycle, as a functional charge carrier transporting unit attached to a saturated polymethacryalamide backbone by a flexible alkyl chain, facilitates resistive switching by the applied voltage. Thin films of the polymer, sandwiched between Al or Au and ITO electrodes, exhibit rewriteable flash memory behavior with bistable conductivity with a setting voltage ranging from 2 to 4.5 V, achieving a current ON/OFF ratio exceeding 100. The device demonstrates a remarkable lifetime and remains persistent for more than 104 seconds under a static voltage of 0.5 V. The main physical mechanisms driving the resistive switching have been attributed to the electric field-induced reorientation of heterocycles, which modulates charge transport, and trapping/detrapping of charges in localized states within the bulk of the polymer. Memory persistence is strengthened by the physical crosslinking caused by hydrogen bonds between amide and carbonyl groups in the aliphatic side chains. This physical network further enhances the thermal and mechanical stability of the PCaPMA in comparison to similar polymers highlighting its potential as a suitable material for organic memory devices.

How Moorfield products helped:

MiniLab 060

Preparation of memory devices

Finally, a 100 nm thick Al or Au top electrode (TE) was deposited by physical vapour deposition (PVD) through a shadow mask using MiniLab 60 (Moorfield, UK) in a vacuum (10−7 mbar) with a deposition rate of 5–10 Å s−1.

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