Inserting Thienyl Linkers into Conjugated Molecules for Efficient Multilevel Electronic Memory: A New Understanding of Charge‐Trapping in Organic Materials

Abstract

The practical application of organic memory devices requires low power consumption and reliable device quality. Herein, we report that inserting thienyl units into D-π-A molecules can improve these parameters by tuning the texture of the film. Theoretical calculations revealed that introducing thienyl π bridges increased the planarity of the molecular backbone and extended the D-A conjugation. Thus, molecules with more thienyl spacers showed improved stacking and orientation in the film state relative to the substrates. The corresponding sandwiched memory devices showed enhanced ternary memory behavior, with lower threshold voltages and better repeatability. The conductive switching and variation in the performance of the memory devices were interpreted by using an extended-charge-trapping mechanism. Our study suggests that judicious molecular engineering can facilitate control of the orientation of the crystallite in the solid state to achieve superior multilevel memory performance.

Surface engineering to achieve organic ternary memory with a high device yield and improved performance

“…11,12 We collected the X-ray diffraction (XRD) patterns for the SA-Bu powder prior to the deposition and for the films deposited on the three types of ITO substrates (Fig. S9†).…”

“…26,40 In our case, the improvements of the ternary device yield and threshold voltages also originate from the reduced mosaicity and smoother morphologies using our extended charge trap mechanism. 12 In our previous study, the charge trapping mechanism was extended by invoking the polarization field of charged traps to explain the organic multilevel electrical switching. Briefly, small organic molecules often crystallize imperfectly through weak intermolecular interactions, leading to the existence of a high density of localized states (charge traps).…”

Nonvolatile resistive memory devices based on ferrocene‐terminated hyperbranched polyimide derived from different dianhydrides

“…The current increases rapidly, due to the charges hoping between the ferroceniums at the terminal and the imide rings at the polymer backbone, to switch the sample to the high conductivity state (ON‐state). At the ON‐state, carriers can be transported directly through the film due to metallization by the space charge filling and thus a conductive channel . Therefore, the I–V curve again follows the ohmic model with a room‐temperature resistance in the order of 10 Ω.…”

Nanostructured Fused Pyrrole Thin Films: Encoding Nano “Bits” with Temporary Remanence

“…It can be visualized that, under an external electric field all the traps get saturated resulting in a trap-free environment wherein the polarized mole cules form a conducting channel, thereby, leading to a sharp increase in current; reflected as the flipped-ON state. [26] The channel allows a free hopping of charge carriers leading to an increase in the current which is observed as high conducting (ON) state. [46] Furthermore, a theoretical experiment is conceptualized to visually elaborate the switching process from a molecular perspective.…”

“…[27] These factors mainly affect the charge carrier transport, [28] ON/OFF ratios, and threshold voltage of the ORMs. [29] Moreover, clarifying the underlying switching mechanism [26] is crucial to achieve reliable and reproducible resistive switching characteristics with minimal technological impasse from a commercialization stand-point. [29] Moreover, clarifying the underlying switching mechanism [26] is crucial to achieve reliable and reproducible resistive switching characteristics with minimal technological impasse from a commercialization stand-point.…”