Rational Design of Small Molecules to Implement Organic Quaternary Memory Devices

Abstract

Organic small‐molecule‐based devices with multilevel electroresistive memory behaviors have attracted more and more attentions due to their super‐high data‐storage density. However, up to now, only ternary memory molecules have been reported, and ternary storage devices may not be compatible with the binary computing systems perfectly. In this work, a donor–acceptor structured molecule containing three electron acceptors is rationally designed and the field‐induced charge‐transfer processes can occur from the donors. Organic quaternary memory devices based on this molecule are successfully demonstrated for the first time. The switching threshold voltages of the memory device are –2.04, –2.73, and –3.96 V, and the current ratio of the “0,” “1,” “2,” and “3” states is 1:101.78:103.47:105.36, which indicate a low possibility of read and write errors. The results represent a further step in organic high‐density data‐storage devices and will inspire the further study in this field.

Surface engineering to achieve organic ternary memory with a high device yield and improved performance

“…After decades of intensive research, many inorganic oxides, 7 polymers 8 and small molecules 9,10 have been found to exhibit multilevel resistive switching behaviours and are thus considered candidate active materials for multilevel RRAMs. However, to enable industrial use, RRAM devices must show good reproducibility, including a high multilevel memory device yield and narrow distribution of OFF/ON1/ON2 switching voltages.…”

“…Unfortunately, numerous studies have explored new RRAM active materials based on the measurements on individual devices, but statistical data on a large batch are rarely reported. 4 Our recent statistical work 9,11–13 demonstrated that the ternary memory yield of organic RRAMs is generally low (∼50%), despite the effectiveness of the molecular design in improving the ternary yield and switching voltage distributions. The frustration of material innovation has urged us to seek other strategies for improving device reproducibility.…”

Nonvolatile Tri‐State Resistive Memory Behavior of a Stable Pyrene‐Fused N‐Heteroacene with Ten Linearly‐Annulated Rings

“…The statistic result reveals that, the yield of ternary devices, as defined by the proportion of achieving output TROS behavior, is about 78 % (see from column‐chart plot in Figure d, left). Recent studies of TROS indicate that the ternary memory yields of some organic‐based materials are usually insufficient (≈50 %) . Regarding this defect, 1 could be considered as an excellent ternary NVM media with satisfactory reproducibility.…”

“…Meanwhile, the side view indicates that the ten‐ring molecular backbone is slightly curved (Figure e, bottom). Combined with the d ‐spacing obtained from XRD, the molecular aromatic cores are estimated to tilt approximately 55° with respect to the lamellar plane (sin θ = d ‐spacing/ M L ) . Figure f illustrates the probable molecular organization model of 1 , in which a tilt angle of 55° between the aromatic cores and lamellar plane is presented, along with the π–π plane separation of 3.47 Å.…”

“…Combined with the d-spacing obtained from XRD, the molecular aromatic cores are estimated to tilt approximately 558 with respectt ot he lamellar plane (sinq = d-spacing/M L ). [44,45] Figure 2fillustrates the probablemolecular organization model of 1,i nw hichatilt angle of 558 between the aromatic cores and lamellar plane is presented, along with the p-p plane separation of 3.47 .T he strong intermolecular p-stacking interactions enable highly-oriented self-assembly behavior of 1 throughout the whole film. As observed from 3D-AFMt opography,t he preferential molecular growth orientations trongly prompted us to investigatet he potential of compound 1 in ORM device.…”