Role of Metal Contacts on Halide Perovskite Memristors

Abstract

Halide perovskites are promising candidates for resistive memories (memristors) due to their mixed electronic/ionic conductivity and the real activation mechanism is currently under debate. In order to unveil the role of the metal contact and its connection with the activation process, four model systems are screened on halide perovskite memristors: Nearly inert metals (Au and Pt), low reactivity contacts (Cu), highly reactive contact (Ag and Al), and pre‐oxidized metal in the form of AgI. It is revealed that the threshold voltage for activation of the memory effect is highly connected with the electrochemical activity of the metals. Redox/capacitive peaks are observed for reactive metals at positive potentials and charged ions are formed that can follow the electrical field. Activation proceeds by formation of conductive filaments, either by the direct migration of the charged metals or by an increase in the concentration of halide vacancies generated by this electrochemical reaction. Importantly, the use of pre‐oxidized Ag+ ions leads to very low threshold voltages of ≈0.2 V indicating that an additional electrochemical reaction is not needed in this system to activate the memristor. Overall, the effect of the metal contact is clarified, and it is revealed that AgI is a very promising interfacial layer for low‐energy applications.

Resistive switching memories with enhanced durability enabled by mixed-dimensional perfluoroarene perovskite heterostructures

“…A commonly accepted mechanism of conduction for halide perovskite resistive switching devices is the formation and rupture of conductive filaments of halide vacancies or metal cations, 45,75–81 which is affected by the choice of electrode. 82–84 Upon illumination, a decrease in the LRS current due to V I / V I X recombination process results in conductive filament annihilation. 85–90 Such abrupt switching can also be the result of conductive bridges between the electrodes through either halide (either I or Br) vacancies or metal cations upon electrochemical metallisation.…”

Capacitive and Inductive Characteristics of Volatile Perovskite Resistive Switching Devices with Analog Memory

“…The OFF state is then maintained throughout the negative polarity scan. This characteristic resistive switching is considered to have a volatile memory where the ON state relaxes back to the OFF state upon the removal or sufficient reduction of the applied voltage. ,, Moreover, by varying the upper vertex voltage of the I – V measurements (Figure b), the device displays a multilevel/multistate resistive switching suitable for analog volatile memory applications in neuromorphic systems. − The memristive response of 20 devices is shown in Figure c, indicating the robustness and reproducibility of the gradual threshold resistive switching of the device configuration. Endurance measurements of a representative device via cycling for 1000 times demonstrates excellent device operational stability with a sustained ON/OFF ratio of ≥1 order of magnitude at a read voltage of V read = 0.6 V (Figure d).…”

“…This characteristic resistive switching is considered to have a volatile memory where the ON state relaxes back to the OFF state upon the removal or sufficient reduction of the applied voltage. 5 , 34 , 35 Moreover, by varying the upper vertex voltage of the I – V measurements ( Figure 2 b), the device displays a multilevel/multistate resistive switching suitable for analog volatile memory applications in neuromorphic systems. 36 − 41 The memristive response of 20 devices is shown in Figure 2 c, indicating the robustness and reproducibility of the gradual threshold resistive switching of the device configuration.…”

Unravelling the Factors Influencing Halide Perovskite Based Switchable Photovoltaics

“…[20][21][22] Complex physical, chemical, electronic, and optoelectronic interactions exist at the LHP/electrode interface. Current research on LHP/metal contacts have focused on band bending, [4,23,24] charge transfer, [25,26] carrier recombination, [27] LHP degradation, [20] various electrode modifications, [28] and their utility in electronic devices. In addition to typical considerations of semiconductor/ electrode interfaces, halide perovskite-based interfaces need to consider intrinsic and extrinsic ionic activities of the LHP as well as the possibility of its reaction with the electrode.…”