Synthesis and tunable electrical behavior of polyfluorene functionalized with triphenylamine and (3-methyl-1-imidazolium-yl)hexyl side chains

Abstract

A novel polyfluorene functionalized with triphenylamine and (3-methyl-1-imidazolium-yl)hexyl side chains, PTOIF, was synthesized. On increasing the content of the ionic functionalities in the polymer structure, the resultant polymer exhibited unique tunable electrical characteristics in electronic devices with the configuration Ta/polymer/ITO. As a result, the PTOIF-1 based device exhibits unipolar memory behaviour with turn-on and turn-off voltages of −3.86 and −2.66 V. Both the PTOIF-2 and PTOIF-3-based devices displayed nonvolatile rewritable memory effects with turn-on and turn-off voltages of −1.69 and 1.08 V (PTOIF-2); and −1.57 and 1.57 V (PTOIF-3). The POIF-based device shows WORM memory performance with a turn-on voltage of −2.14 V. Local electrostatic fields provided by the ionic functionalities in the polymer greatly affect the size, shape and statistical distribution of the current filaments responsible for the switching to the on state.