Improved Performance of the Al₂O₃-Protected HfO₂–TiO₂ Base Layer with a Self-Assembled CH₃NH₃PbI₃ Heterostructure for Extremely Low Operating Voltage and Stable Filament Formation in Nonvolatile Resistive Switching Memory

Abstract

Herein, we report intriguing observations of an extremely stable nonvolatile bipolar resistive switching (NVBRS) memory device fabricated using HfO 2 −TiO 2 topologically protected by Al 2 O 3 as a stacked base layer for a CH 3 NH 3 PbI 3 (MAPI) electrolyte layer sandwiched between Ag and fluorine-doped tin oxide (FTO) electrodes. MAPI has been successfully synthesized by a rapid microwave−solvothermal (MW-ST) method within 10 min at 120 °C without requiring any inert gas atmosphere using lowcost precursors and solvents. Subsequently, MAPI powders are dissolved in aprotic solvents (DMF/DMSO = 8:2), and a spin-coated thin film is allowed to recrystallize upon annealing at 120 °C via a solution-based nanoscale self-assembly process. The fabricated memory device with the Ag/MAPI/Al 2 O 3 /TiO 2 -HfO 2 /FTO configuration shows an enhanced resistance ratio of 10 5 for >10 4 s at an extremely lower operating voltage (SET +0.2 V, RESET −0.2 V) when compared to that of the pristine MAPI device (±1 V, 10 2 , 10 4 s). We show that the memory device also exhibits a remarkable endurance of ≥3500 cycles due to the Al 2 O 3 robust coating on the HfO 2 −TiO 2 layer, facilitating prompt heterojunction formation. Thus, the adopted innovative strategies to prepare structurally and optically stable (∼1.5 years) MAPI under high-humid conditions could offer enhanced performance of NVBRS memory devices for medical, security, internet of things (IoT), and artificial intelligence (AI) applications.

Revealing the effect of substitutional cation doping in the A-site of nanoscale APbI3 perovskite layers for enhanced retention and endurance in optoelectronic resistive switching for non-volatile bipolar memory devices

“…However, upon illumination, V I vacancies move randomly, thus creating a high built-in electric field thus requiring an increased V RESET to dissociate the CFs. 23 Thus, the variation in the operating voltage upon illumination attributed to the randomness of the halide vacancies migration, further confirms the presence of the V I -based CF formation for the resistive switching performance. 55,56 izes the complete device performance of the fabricated Ag/APbI 3 /FTO (A = MA + , FA + , MAFA + , CsMA + , and CsMAFA + ) non-volatile bipolar resistive switching memory devices.…”

“…20 For more than a decade, our research group has effectively adopted the microwave-assisted hydrothermal/solvothermal (MW-HT/ST) technique to prepare various advanced functional materials within a few minutes. [20][21][22][23] In the present study, we successfully demonstrate the effective doping of various inorganic and organic cations in the A-site of APbI 3 (A = MA + , FA + , MAFA + , CsMA + , and CsMAFA + ) perovskite structure to form methylammonium lead iodide (MAPI), formamidinium lead iodide (FAPI), methyl ammonium formamidinium lead iodide (MAFAPI), cesium methylammonium lead iodide (CsMAPI) and cesium methylammonium formamidinium lead iodide (CsMAFAPI) powders using an energy-efficient and ultra-fast MW-ST method within 10 minutes at 120 °C without requiring any inert-gas atmosphere. The as-synthesized MHP powders were dissolved in aprotic solvents, DMF : DMSO (8 : 2) and subsequently, were allowed to recrystallize via the solution-based nanoscale selfassembled process into a thin film using the facile and costeffective spin-coating technique, upon annealing at 120 °C.…”

Enhanced Solar‐Photo(Electro)catalysis of Microwave‐Hydrothermal Synthesized BiVO4, ms‐BiVO4/Reduced Graphene Oxide/Ag3PO4 Nanohybrid: Crystalline Phase‐Dependent Interfacial Charge Carrier Dynamics

“…At constant ramp time of 10 min, an increase in temperature of precursors from 313 to 394 K is observed, which supplies enough standard total free energy of activation (ΔG ╪ ) ( Figure 1 b, B‐1) calculated by Eyring equation. [ 23–25 ] Consequently, it enhances the activation energy ( E a ) of the reactants, leading to the diffusion in crystallites of tz ‐BiVO 4 phase (B‐1). The reaction rate is calculated by Equation (1)where T stands for absolute temperature in Kelvin, k is rate constant, k B is Boltzmann constant, h is the Planck's constant, R denotes universal gas constant, and Δ G ╪ denotes the standard total Gibbs free energy of activation difference between the reactants and transition state, i.e., energy available to do useful work.…”

“…At constant ramp time of 10 min, an increase in temperature of precursors from 313 to 394 K is observed, which supplies enough standard total free energy of activation (ΔG ǂ ) (Figure 1b, B-1) calculated by Eyring equation. [23][24][25] Consequently, it enhances the activation energy (E a ) of the reactants, leading to the diffusion in crystallites of tz-BiVO 4 phase (B-1). The reaction rate is calculated by Equation ( 1)…”

“…However, the effect of microwave exposure can be considered athermal, as previously reported. [23][24][25][26]…”