Synthesis and WORM Memory Performance of Polycarbazole Derivatives with Different Electron Acceptors in the Side Chain

Three soluble D-A type polycarbazole derivatives with different electron acceptors in the side chain,including poly(9-(2-hexyldecyl)-9H-carbazole)-(9-(4-nitrophenyl)-9H-carbazole)(PCz-NO₂),poly(9-(2-hexyldecyl)-9H-carbazole)-(4-(9H-carbazole-9-yl)benzaldehyde) (PCz-CHO),and poly(9-(2-hexyldecyl)-9H-carbazole)-(4-(9H-carbazole-9-yl)benzonitrile) (PCz-CN),were synthesized through the Suzuki coupling reaction.These polymers-based electronic devices with a configuration of Al(200 nm)/polymer (90 nm)/Indium-Tin Oxide (ITO) had representative bistable electrical switching behavior and non-volatile write-once read-many-times (WORM)memory performance.When the optical bandgap of conjugated polymer was increased (2.26 eV(PCz-NO₂)→2.79 eV(PCz-CHO)→3.20 eV(PCz-CN)),the threshold voltage of the corresponding electronic device gradually increased (-1.70 V→-1.81 V→-1.89 V),whereas the ON/OFF current ratio was changed from 6.63×10⁴ for PCz-NO₂ to 4.08×10⁴ for PCz-CHO and to 5.68×10³ for PCz-CN.Among these three derivatives,PCz-CN exhibited the biggest turn-on voltage and the lowest ON/OFF current ratio.