A Homochiral Neutral Organic Molecule as Active Ferroelectric for Memtransistor

Abstract

Molecular ferroelectrics are of enormous interest due to their ease of synthesis and simplicity in device fabrication. Here, the non-volatile memory effect in a polycrystalline thin film of the single-component ferroelectric material naphthalene monoimide (NMI), 6-bromo-2-(1-phenylethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (NMI-RBn), obtained by introducing the enantiomeric α-methylbenzyl (RBn) substituents on the NMI backbone is demonstrated. Both NMI-RBn and NMI-SBn derivatives crystallized in the monoclinic P21 space group. The PFM and P-E hysteresis loop measurements revealed the ferroelectric nature of NMI-RBn. Computational studies elucidate a spontaneous polarization mechanism with a calculated polarization of 4.6 µC cm−2 along the b-axis. The NMI-RBn has subsequently been studied for memtransistor application, where the developed field-effect transistor (FET) device exhibits gate-tunable multi-state non-volatile rewritable memory states. By varying the gate voltage, the device can be reconfigured to a non-volatile memory with a tunable memory window of up to 65 V, current modulation between memory states of 104, retention time greater than 20,000 s, and a volatile memory emulating neuronal learning behavior. These findings highlight the potential of homochiral single-component organic ferroelectrics for applications in ferroelectric FETs and neuromorphic memory devices.