Tailoring the Resistive Switching WORM Memory Behavior of Functionalized Bis(triphenylamine).

To better understand the structure-property relationship and the significance of the donor-acceptor (D-A) system in resistive memory devices, a series of new organic small molecules with A-π-D-π-A- and D-π-D-π-D-based architecture comprising a bis(triphenylamine) core unit and ethynyl-linked electron donor/acceptor arms were designed and synthesized. The devices with A-π-D-π-A structures exhibited write-once-read-many memory behavior with a good retention time of 1000 s while those based on D-π-D-π-D molecules presented only conductor property. The compound with nitrophenyl substitution resulted in a higher ON/OFF current ratio of 104, and the fluorophenyl substitution exhibited the lowest threshold voltage of -1.19 V. Solubility of the compounds in common organic solvents suggests that they are promising candidates for economic solution-processable techniques. Density functional theory calculations were used to envision the frontier molecular orbitals and to support the proposed resistive switching mechanisms. It is inferred that the presence of donor/acceptor substituents has a significant impact on the highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels of the molecules, which affects their memory-switching behavior and thus suggests that a D-A architecture is ideal for memory device resistance switching characteristics.

Butterfly-Like Triarylamines with High Hole Mobility and On/Off Ratio in Bottom-Gated OFETs.

Highly π-extended butterfly-shaped triarylamine dyads with aryleneethynylene spacer were constructed using an efficient synthetic route. These aryleneethynylene-bridged dyads are highly fluorescent and exhibited high HOMO levels, and low bandgaps, which are suitable for high-performance p-type OFETs. The field-effect transistors were fabricated through a solution-processable method and exhibited promising p-type performance with field-effect mobility up to 4.3 cm2 /Vs and high Ion/off of 108 under ambient conditions.

Hexaarylbenzene based high-performance p-channel molecules for electronic applications.

Hexaarylbenzene-based molecules find potential applications in organic electronics due to wider energy gap, high HOMO level, higher photoconductivity, electron-rich nature, and high hole-transporting property. Due to the unique propeller structure, these molecules show low susceptibility towards self-aggregation. This property can be tailored by proper molecular engineering by the incorporation of appropriate groups. Therefore, hexaarylbenzene chromophores are widely used as the materials for high-efficiency light-emitting materials, charge transport materials, host materials, redox materials, photochemical switches, and molecular receptors. This review highlights the diverse structural modification techniques used for the synthesis of symmetrical and unsymmetrical structures. Also, the potential applications of these molecules in organic light-emitting diodes, organic field-effect transistors, organic photovoltaics, organic memory devices, and logic circuits are discussed.