Abstract:

Photoelectric resistive switching memory (RRAM) is the most promising competitor in the next generation of non-volatile memory (NVM) owing to its miniaturization, integration, and versatility advantages. A low-temperature spin coating method is deployed to synthesize inorganic CsPbBr₃ quantum dots (QDs) with green fluorescence. Then, flexible photoelectrical dual-controlled Ag/CsPbBr₃ QDs/indium tin oxide (ITO) RRAM devices with high efficiency are prepared, in which the switching behavior is modified by both electric field and light illumination. The as-prepared device demonstrated forming-free bipolar resistive switching behavior in the presence and absence of light. The switching voltages (V_SET) show significant reductions compared to the dark condition, and the hysteresis windows considerably increase under illumination. These indicate a higher ON/OFF ratio and lower energy consumption under illumination than in the dark for the Ag/CsPbBr₃ QDs /ITO device. The ON/OFF ratio of the Ag/CsPbBr₃ QDs /ITO device is about 3.2×10³ under illumination, about 24 times higher than that in the dark state. The V_SET is 2.88 V, approximately 13.3% lower than the dark state. These results are further confirmed by the resistive switching behavior of the 36 memory cells randomly selected in the Ag/CsPbBr₃ QDs /ITO device. Moreover, the devices exhibit good fatigue and retention performance. No noticeable degradation occurre in the high resistance state (HRS) and low resistance state (LRS) even after 500 consecutive cycles. The resistance remain stable for a long retention time exceeding 5000 s. The large ON/OFF ratio, good endurance, and retention properties of the Ag/CsPbBr₃ QDs: GO/ITO device are sufficient for a photoelectric regulation NVM device. Based on the double logarithmic fitting curves during the switching process, it is assumed that the device has the same conduction mechanism under dark and illumination conditions, which is dominated by both ohmic behavior and space charge limited current (SCLC) mechanism in the HRS, and only by the ohmic conduction in the LRS. The primary resistive switching mechanism in the Ag/CsPbBr₃ QDs/ITO devices is enabled by the formation and rupture of the hybrid conductive filament composed of Br^- vacancies and Ag atom owing to both Br^- and Ag⁺ ion migration under an electric field. The main reason for the declining LRS resistance, resulting in the increment of the ON/OFF ratio and V_SET of the above devices, is derived from the increasing photocurrent promoted by the decreasing defect density in CsPbBr₃ QDs films under illumination. High-efficiency photoelectronic regulatory perovskite materials will improve the development of high-density memory RRAM technology.

Key words: Perovskite, Photoelectric regulation, Resistive switching memory, CsPbBr₃, Ion migration