Organic nonvolatile memory devices utilizing intrinsic charge-trapping phenomena in an n-type polymer semiconductor

Abstract

Charge trapping is an undesirable phenomenon and a common challenge in the operation of n-channel organic field-effect transistors. Herein, we exploit charge trapping in an n-type semiconducting poly (naphthalene diimide-alt-biselenophene) (PNDIBS) as the key operational mechanism to develop high performance, nonvolatile, electronic memory devices. The PNDIBS-based field-effect transistor memory devices were programmed at 60 V and they showed excellent charge-trapping and de-trapping characteristics, which could be cycled more than 200 times with a current ratio of 103 between the two binary states. Programmed data could be retained for 103 s with a memory window of 28 V. This is a record performance for n-channel organic transistor with inherent charge-trapping capability without using external charge trapping agents. However, the memory device performance was greatly reduced, as expected, when the n-type polymer semiconductor was end-capped with phenyl groups to reduce the trap density. These results show that the trap density of n-type semiconducting polymers could be engineered to control the inherent charge-trapping capability and device performance for developing high-performance low-cost memory devices.