Inducing a high twisted conformation in the polyimide structure by bulky donor moieties for the development of non-volatile memory
Journal
European Polymer Journal
Journal Volume
49
Journal Issue
10
Pages
3377-3386
Date Issued
2013
Author(s)
Abstract
Two polyimides, PI(DAT-6FDA) and PI(DAPT-6FDA), from N-(2,4-diaminophenyl)- N,N-diphenylamine (DAT) or N-(4-(2′,4′-diaminophenoxy)phenyl-N,N- diphenylamine (DAPT) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) were prepared to clarify the structural effect on the resulting memory properties. The memory device based on PI(DAT-6FDA) showed an unstable volatile behavior, while the device based on PI(DAPT-6FDA) with a more bulky donor (D) unit exhibited a stable non-volatile FLASH type memory characteristic with a long retention time over 104 s. The theoretical simulation based on the density functional theory (DFT) suggested that the greater distinct charge separation between the ground and charge transfer (CT) states led to a highly stable memory behavior. Also, it was clarified that PI(DAPT-6FDA) had a highly twisted conformation compared to PI(DAT-6FDA) in the ground state, and a more twisted dihedral angle between the D and acceptor (A) units was induced in the CT state, which led to the non-volatile memory characteristic. © 2013 Elsevier Ltd. All rights reserved.
Type
journal article