Enhanced resistive switching performance in yttrium-doped CH3NH3PbI3 perovskite devices.

In this study, yttrium-doped CH3NH3PbI3 (Y-MAPbI3) and pure CH3NH3PbI3 (MAPbI3) perovskite films have been fabricated using a one-step solution spin coating method in a glove box. X-ray diffractometry and field-emission scanning electron microscopy were used to characterize the crystal structures and morphologies of perovskite films, respectively. It was found that the orientation of the crystal changed and the grains became more uniform in Y-MAPbI3 film, compared with the pure MAPbI3 perovskite film. The films were used to prepare the resistive switching memory devices with the device structure of Al/Y-MAPbI3 (MAPbI3)/ITO-glass. The memory performance of both devices was studied and showed a bipolar resistive switching behavior. The Al/MAPbI3/ITO device had an endurance of about 328 cycles. In contrast, the Al/Y-MAPbI3/ITO device exhibited an enhanced performance with a long endurance up to 3000 cycles. Moreover, the Al/Y-MAPbI3/ITO device also showed a higher ON/OFF ratio of over 103, long retention time (≥104 s), lower operation voltage (±0.5 V) and outstanding reproducibility. Additionally, the conduction mechanism of the high resistance state transformed from space-charge limited current for a Y free device to the Schottky emission after Y doping. The present results indicate that the Al/Y-MAPbI3/ITO device has a great potential to be used in high-performance memory devices.

Enhanced Memristive Performance of Double Perovskite Cs2 AgBiBr6-x Clx Devices by Chloride Doping.

Mixed halide perovskites are promising memristive materials because of their excellent electronic-ionic properties. In this work, lead-free Cs2 AgBiBr6-x Clx (x=0, 0.2, 0.4, 0.6, 0.8, 1.0) double perovskite films were fabricated using a one-step solution spin-coating method in air. Moreover, the ITO/Cs2 AgBiBr6-x Clx /Al sandwich-like devices are fabricated to investigate the memristive behaviors. The present memristors exhibit nonvolatile and bipolar resistive switching behaviors without electroforming process. Interestingly, as the chloride content increases, the ON/OFF ratio of the device increases from 103 to 104 , the average SET voltage and the RESET voltage decrease from -0.40 V to -0.21 V and from 1.55 V to 1.34 V, respectively. In addition, resistance states of devices can be maintained after 100 switching cycles and 104  s of reading. This study provides new possibility for the development of low-power and environmentally friendly memristors.