Fabrication And Characteristics Of Organic Electrically Bistable Memory Device With Znic-based Semiconductor Nanocrystals

As an emerging memory technology, organic electrically bistable device fabricatedutilizing hybrid inorganic/organic nanocomposites have become particularly interesting due totheir promising applications in next generation nonvolatile memory devices with variousadvantages of low-power consumption, low cost and simple processing. But the impact ofinorganic nanoparticles （NPs） on the bistable effect has not been well understood, and thecharge-transport mechanisms need to be further investigated. We fabricated bistable devicesutilizing core/shell ZnO/SiO₂NPs embedded between two PVP layers, and investigated thevariations in the electrical properties due to a SiO₂shell layer. The organic light emittingbistable memory device with ZnS quantum dots （QDs） embedded in a PVP layer was alsofabricated and the write-once-read-many-times memory mechanism was preliminarycharacterized. Detailed results are as follows:1、A new electrical bistable device with better switch effect and environmental stabilitywas prepared using core/shell-type ZnO/SiO₂NPs embedded between twopoly-4-vinyl-phenol （PVP） layers by using a spin-coat technique. Compared with the deviceexcluding NPs interlayer, the device showed improved reproducible electrical bistability andnegative differential resistance （NDR） effects. The electrical bistability properties werediscussed in detail based on current-voltage （I-V） characteristics at different applied reversevoltage. The space-charge-limited-current （SCLC） conduction model and Ohmic conductionmodel were proposed to explain the carrier behavior of the device under alternately appliedpositive and negative voltage. The charge trapping and de-trapping process of ZnO NPs canbe modulated by the voltage polarity and were further validated by the I-V data. Incomparison with the hubrid device, the all-inroganic bistable device was fabricated withcore/shell-style ZnO/SiO₂NPs and its carrier transport mechanisms were also concerned. Forthe role of the SiO₂shell in the memory device, we compared the memory performance of thetwo devices fabricated with ZnO core NPs and core/shell ZnO/SiO₂NPs embedded in twoPVP layers on the basis of the I-V and I-t results. The measurements of the devices showedthat the ON/OFF ratio and the retention time for devices fabricated utilizing core/shellZnO/SiO₂NPs show greater benefit than that for devices fabricated utilizing ZnO NPs.2、The organic electrically bistable devices were fabricated utilizing ZnS QDs embeddedin a PVP layer. The write-once-read-many-times performance was characterized anddiscussed.3、We fabricated organic light emitting bistable memory device with ZnS QDs. Theelectroluminescence and memory effect and the operation mechanism were preliminarystudied on the device.