Nonvolatile polymer memory device based on bistable electrical switching in a thin film of poly(N-vinylcarbazole) with covalently bonded C60

Abstract

A functional polymer (PVK-C60), containing carbazole moieties and fullerene moieties in a molar ratio of about 100:1, was synthesized by covalent tethering of C60 to poly(N-vinylcarbazole) (PVK). The molecular structure and composition of PVK-C60 were characterized by FTIR, Raman, and UV-vis absorption spectroscopy, gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CyV). It was observed that the C60-modified PVK exhibited an enhanced glass-transition temperature and good solubility in organic solvents such as toluene, tetrahydrofuran, chloroform, and N,N-dimethylformamide (DMF). The polymer memory exhibited an ON/OFF current ratio of more than 105 and write/erase voltages around -2.8 V/+3.0V. Both the ON and OFF states were stable under a constant voltage stress of -1 V for 12 h and survived up to 108 read cycles at -1 under ambient conditions.