Electronic effect of terminal acceptor groups on different organic donor–acceptor small-molecule based memory devices

Abstract

In this work, three new organic donor–acceptor small-molecules, in which bicarbazole served as the electron donor, and benzothiazole, nitryl or 1,1′-dicyanovinyl were used as the electron acceptor, were designed and synthesized in order to fabricate sandwiched memory devices. Acceptors with a variable electron-delocalized extent and electron-withdrawing strength were attached to the molecular backbone in order to investigate the effect on the devices switching behavior. The bi-n-butylcarbazole benzothiazole (BCZ-BT) based memory device exhibited volatile static random access memory (SRAM) switching behaviour, while the devices based on bi-n-butylcarbazole nitryl (BCZ-NO2) was found to exhibit stable nonvolatile write-once-read-many-times (WORM) data storage characteristics and the bi-n-butylcarbazole dicyanovinyl (BCZ-CN) device acted as rewritable flash memory with a higher ON/OFF current ratio of about 104. Therefore, tunable data storage devices synthesized by adjusting the terminal acceptor groups offer feasible guidance for the rational design of organic molecules to achieve superior memory performance.

Fused Pyrrole Core: A New Class of Quadrupolar Organic Moieties as Potential Resistive Memory Elements

“…16 Thereafter, positive potential scans (sweep 4, sweep 5, 0 to 4.0 V) was performed to check whether the device could be switched back to the OFF state (data erase process). 17 The ITO/DNPP/Al device however showed no change-over to the high resistivity state even with a scan potential going up to +10 V (Figure 4(b)). Successive scans to validate retention and stability demonstrates that the device retains information for 10 6 s without any signifi cant degradation in the ON state as seen from Figure 4(c).…”

“…Nonetheless, the ON state can be switched back to the OFF state during a positive sweep at 2.0 V, and could be again switched back ON in the next cycle, a characteristic behavior of non-volatile flash memory. 17 The validation was carried out on multiple independent devices fabricated under similar set of conditions. The endurance performance (reliability) of 500 cycles observed with ON/OFF ratio maintained as shown in Figure 5(b)-(c) was quite appreciable given the lack of device encapsulation.…”

“…The device response under externally applied bias could be predicted by considering the energy barriers, injection of electrons/holes, trap states involved, dipole moments, role of space-charge polarizations that signifi cantly contributes at various stages of the sweep. 15,17 In the case of ITO/DNPP/Al, comparable charge injection barriers at the ITO ( )→HOMO ( Δ 0.69 eV) and the Al ( )→LUMO ( Δ 0.67 eV) implies equal possibility of both hole and electron injections. At potentials < -0.5 V, Schottky barriers exist and the device remains in the OFF state (high resistivity at the active electrode-organic layer interface).…”

The Effect of Random and Block Copolymerization with Pendent Carbozole Donors and Naphthalimide Acceptors on Multilevel Memory Performance

“…The second approach involves the development of multilevel OMDs (e.g., ternary devices), which would allow the corresponding storage density to be increased to 3 n , hundreds of millions of times greater than that of a binary system, which offers a density of 2 n . In previous reports regarding OMDs, several conduction mechanisms, such as redox, filament formation, conformational change, charge trapping, and charge transfer, have been successfully introduced to interpret the properties of memory devices. Therefore, we wondered whether ternary memory performance could be realized through combining two individual conduction mechanisms into a single polymer.…”

Tunable memory performances of the porphyrin terminated hyperbranched polyimides

“…(In the HBPIs, the D moiety can locate at their backbone and terminal structure.) The modification of D moiety includes the introduction of different substituent, the combination of different D moieties as a new one, and isomerization of the chemical structure of D moieties . The memory behaviors of the HBPIs can be tuned from volatile memory (dynamic random‐access memory, DRAM, and static random‐access memory, SRAM) to nonvolatile memory (write once read many times memory, WORM, and flash) by the modification of D moiety .…”