Synthesis and memory device characteristics of new sulfur donor containing polyimides
Journal
Macromolecules
Journal Volume
42
Journal Issue
13
Pages
4456-4463
Date Issued
2009
Author(s)
Abstract
The synthesis and memory device characteristics of two new poly[2,7-bis(phenylenesulfanyl)thianthrene−hexafluoroisopropylidenediphthalimide] (APTT-6FDA) and poly[4,4′-thiobis(p-phenylenesulfanyl)−hexafluoroisopropylidenediphthalimide] (3SDA-6FDA) are reported. The sulfur-containing APTT and 3SDA as electron donor were designed to enhance electron-donating and charge-transporting characteristics for the device application. The optical band gaps of APTT-6FDA and 3SDA-6FDA estimated from the absorption edges were 3.51 and 3.46 eV, which probably resulted from the difference in the structural coplanarity. The estimated energy levels (HOMO, LUMO) of APTT-6FDA and 3SDA-6FDA were (−5.55, −2.04) and (−5.71, −2.25) eV, respectively. The memory device with the configuration of ITO/polymers/Al showed nonvolatile memory characteristics with the low turn-on threshold voltages of 1.5 V(APTT-6FDA) and 2.5 V(3SDA-6FDA), probably resulting from the difference in the HOMO energy level. Also, the memory devices could be repeatedly written, read, and erased. The on/off current ratios of the devices were all around 104 in ambient atmosphere. The relatively higher dipole moments of the sulfur-containing polyimides compared to the triphenylamine-based polyimide provided a stable CT complex for the flash memory device. The above electronic properties were further confirmed by the density functional theory (DFT) method at the B3LYP level with the 6-31G(d) basis set. The present study suggested that the new sulfur-containing polyimides would have potential applications for memory devices.
SDGs
Type
journal article