Insertion of conjugated bridges in organic backbone for better multilevel memory performance: The role of alkynyl group

• Two A–D–A type small organic molecules differed by alkynyl bridges are synthesized.
• The insertion of alkynyl group causes better molecular stacking and crystallinity.
• Both the fabricated devices show nonvolatile ternary WORM memory behaviors.
• Device of alkynyl bridges has higher ternary yield and lower threshold voltages.

Two acceptor–donor–acceptor (A–D–A) type organic small molecules, 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(N-(4-nitrophenyl)-N-phenylaniline) (NTPA2BT) and 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diylbis(ethyne-2,1-diyl))bis(N-(4-nitrophenyl)-N-phenylaniline) (NTPA2EBT), differing by an alkynyl bridge, were designed, synthesized and fabricated into resistive random access memory devices. Compared with NTPA2BT, the fabricated memory device based on NTPA2EBT of extra alkynyl bridges presents nonvolatile ternary memory performance with lower threshold voltages, better stability and higher reproducibility. X-ray diffraction (XRD) patterns show that the NTPA2EBT film is much more regularly crystallized. Meanwhile, the photophysical and electrochemical properties indicate that the insertion of conjugated bridges in molecular structures could help to improve data storage characteristics with lower power consumption. Our results show that alkynyl is an important group to tailor organic molecules to achieve excellent data storage devices.

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