Synthesis and Resistive Switching Performance of Benzothiazole-Based D-A Type Conjugated Polymer
A novel benzothiadiazole-based donor-acceptor type polymer,resistive random access memory(RRAM)material,poly{[4,4'-(2,7-diphenyl-9H-fluorene-9,9-diyl)bis(N,N-diphenylaniline)]-alt-[4,7-bis(4-dodecyl-5-vinylthiophen-2-yl)benzo[c][1,2,5]thiadiazole]}(PFVT)was synthesized.By using PFVT as the active layer,the as-fabricated electronic device with a configuration of Al/PFVT/ITO(ITO:indium tin oxides)exhibites a nonvolatile RRAM performance.During 50 consecutive cycle-to-cycle measurements,the observed average switch-on voltage,switch-off voltage and ON/OFF current ratio are(-0.54±0.01)V,(2.42±0.05)V,and 1.5×103,respectively.The cycle-to-cycle variation for the programming voltage is less than 2.1%,suggesting excellent reliability.After thermal annealing at 200℃,the switch-on and switch-off voltages decrease to(-0.49±0.01)V and(2.27±0.02)V,respectively,due to the enhanced material crystallinity.The switching mechanism can be assigned to the intramolecular charge-transfer occurred in the materials system.The ON and OFF-state currents can be fitted by the Ohmic current model and space-charge-limited current model,respectively.The switch-on voltage is highly associated with the bandgap of the materials.For comparison purpose,4,4′-(2,7-diphenyl-9H-fluorene-9,9-diyl)bis(N,N-diphenylaniline)was replaced with phenyl group to synthesize poly[4-(4-dodecyl-5-((E)-4-methylstyryl)thiophen-2-yl)-7-(4-dodecyl-5-((E)-prop-1-en-1-yl)thiophen-2-yl)benzo[c][1,2,5]thiadiazole](PPVT).In contrast to PFVT,PPVT also shows the similar RRAM performance,with a bigger switch-on voltage and a smaller ON/OFF current ratio.Replacement of bulky fluorene unit with phenyl unit leads to a sharp decrease in the thermal stability of the material and an increase in the bandgap.
benzothiadiazoleconjugated polymerresistive random access memorymaterials synthesischarge transfer
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