The Creation Of High-Performance Crystalline Organic Memristors Based On Viologen And Pyrene Derivatives

The coming of the information era requires high-performance storage media with clearly resistive switching（RS）mechanisms.However,the memristor media still have problems such as poorly comprehensive performances and ambiguous mechanisms,which cannot meet the requirements of practical applications.The inherent structural flexibility and reversibility within crystalline organic materials/HOFs provide great potential in the field of resistive switching（RS）,but not well explored yet.In this thesis,we focus on the research on the relationship between the structures and RRAMs/proton conduction performances through molecular design-cum-synthesis strategy,which provides theoretical basis and new research ideas for the development of high-performance crystalline material/HOFs based RRAMs or proton conductors.The specific results are summarized as follows:1.The flexible and bendable macrocycle-based HOF（HOF-FJU-35）was obtained by combining semi-rigid and rigid organic building blocks.Due to its inherent structural flexibility,HOF-FJU-35 exhibits resistive random-access memory（RRAM）effect with set voltage（（27）7.5 V）,high ON/OFF ratio（>10⁶）,and low operating current(10^-8A)and leakage current(10^-14A),which provides a good foundation for low-energy storage.2.We have successfully synthesized a polycatenated HOF material（HOF-FJU-52）featuring asymmetric hydrogen bonds dimers,as well as infinite but switchableπ-πstacking paths from staggered benzoic groups on their skeletons.At room temperature,HOF-FJU-52 exhibits resistive random-access memory（RRAM）effect with ultrafast switching speed（～34 ns）,ultralow switching energy（～374 z J）,excellent endurance（>10⁶cycles）and ultrahigh ON/OFF ratio（～10⁹）,whose comprehensive performance is comparable to the state-of-the-art RS materials.SCXRD of HOF-FJU-52 after an external electric field applied reveals its RS behaviors can be assigned to the migration of two shared protons in the asymmetric hydrogen bond dimers,which triggers the switching of the infiniteπ-πstacking pathway.Such RS mechanism is further confirmed by XPS,DFT calculations and control experiments.More interestingly,upon cooling and heating,the RS behaviors of our single crystal HOF device can switch between the RRAM and write-once-read-many-times memory（WORM）,and the switching shows very interesting hysteresis loop as the structural change in the single crystal-single crystal transformation for the first time.3.We have synthesized an organic cocrystal of HPNPS-1 composed of a new organic molecule of sodium 3-hydroxy-2,5,6,8,9-penta nitro pyrene-1-sulfonate（HPNPS）and a redox-active molecule of CH₃L.HPNPS-1 is further tailored by esterification reaction,yielding HPNPS-4 with more steric hindrance on its periphery,which offers great opportunity for understanding how steric hindrance affectπ-πstacking motifs to realize RS behaviors.HPNPS-4 displays high ON/OFF ratio,fast switching speed,low switching energy（6.26 p J）,excellent endurance（>10⁶ cycles）,low switching voltage and multilevel resistance tuning,which lays the foundation for its applications in hardware artificial neural network（ANN）.4.We have successfully synthesized three organic cocrystal by selecting different viologen derivatives and 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt（HPTS）.Then we also investigate the single-crystal proton conductivity of these three materials.It is worth noting that these materials have the highest proton conductivity along theirπ-πstacking pathway.The ultrahigh proton conductivity of HPNPS-N single crystal reaches to 7.96S/cm alongπ-πstacking interactions pathway,which is the highest among all reported organic crystalline materials.In a word,these cocrystal materials demonstrate how regulating theπ-πstacking interactions inπ-complexes serves as a route towards controlling their proton conduction performance.