Organolead halide perovskites exhibit excellent optoelectronic and photovoltaic properties such as a wide range of light absorption and tunable band gaps. However, the presence of toxic elements and chemical instability under an ambient atmosphere hindered lead halide perovskites from real device applications because of environmental issues and stability. Here, we demonstrate a resistive switching memory device based on a lead-free bismuth halide perovskite (CH3NH3)3Bi2I9 (MABI). The active layer of the device can be easily prepared by solvent engineering. The nonvolatile memory based on MABI layers has reliable retention properties (∼104 s), endurance (300 cycles), and switching speed (100 ns), as well as environmental stability. Moreover, the control of the compliance current leads to multilevel data storage with four resistance states, which can be applied to high-density memory devices. These results suggest that MABI has potential applications in information storage.

The demand for high memory density has increased due to increasing needs of information storage, such as big data processing and the Internet of Things. Organic-inorganic perovskite materials that show nonvolatile resistive switching memory properties have potential applications as the resistive switching layer for next-generation memory devices, but, for practical applications, these materials should be utilized in high-density data-storage devices. Here, nanoscale memory devices are fabricated by sequential vapor deposition of organolead halide perovskite (OHP) CH NH PbI layers on wafers perforated with 250 nm via-holes. These devices have bipolar resistive switching properties, and show low-voltage operation, fast switching speed (200 ns), good endurance, and data-retention time >10 s. Moreover, the use of sequential vapor deposition is extended to deposit CH NH PbI as the memory element in a cross-point array structure. This method to fabricate high-density memory devices could be used for memory cells that occupy large areas, and to overcome the scaling limit of existing methods; it also presents a way to use OHPs to increase memory storage capacity.

Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3−xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3−xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3−xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3−xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br− (0.23 eV) than for I− (0.29–0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film.

Increasing demands for information‐storage capacity and for miniaturization of memory cells have driven exploration of new‐generation data storage devices, because the conventional Si‐based memory technology is approaching its fundamental physical limits. Hybrid materials and novel device structure may lead to a paradigm shift toward memory devices that have high density, multifunctionality, and low power consumption. Here, the structure and operation mechanism of resistive switching memory devices are described, then recent advances in hybrid materials (e.g., graphene‐based polymer composites, organic–inorganic hybrid perovskite materials) for fabrication of these devices are summarized. How to increase the ON/OFF ratio and the density of memories, and to decrease programming voltage by selecting appropriate active materials, and engineering the active layers, are also demonstrated. Finally, the current challenges and future directions in memory devices based on hybrid materials are summarized.

Abstract2D organic–inorganic hybrid perovskites (OIPs) hold great promise for electronics and optoelectronics due to structural diversity, high photoluminescence, and tunable bandgap. Moreover, integrating 2D OIPs with the 2D materials including graphene, transition metal dichalcogenide, and other OIPs gives opportunities for various options in constructing new types of heterojunctions with novel functionalities such as enhanced charge transport properties or chemical stability. Here, a sequential vapor deposition method is presented to fabricate 2D OIP lateral heterostructure films (C4H9NH3)2PbI4 (BA2PbI4)–(C4H9NH3)2(CH3NH3)Pb2I7 (BA2MAPb2I7) for photodetector applications. The lateral heterostructure is realized using thermal evaporation to deposit lead iodide (PbI2) films, then exploiting vapor transport of organic vapor to form BA2PbI4, BA2MAPb2I7, and self‐aligned lateral heterostructure. A photodetector based on the lateral structure (BA2PbI4–BA2MAPb2I7) shows larger photocurrent and higher on/off ratio (>102) than those of single material‐based devices (BA2PbI4, BA2MAPb2I7). This method to fabricate 2D OIP lateral heterostructure suggests a simple way to synthesize 2D perovskite heterostructure and may open the possibility of 2D OIP perovskites to be integrated in emerging optoelectronic devices.