Improvement of resistive memory properties of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/CH₃NH₃PbI₃ based device by potassium iodide additives

In this study, a glass/indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/CH₃NH₃PbI₃ (MAPbI₃)/poly(methyl methacrylate) (PMMA)/Al nonvolatile memory device is demonstrated. The MAPbI₃ film is prepared on top of the PEDOT:PSS by a two-step process, showing a bipolar resistive switching character. Because PEDOT:PSS is widely used as a hole transporting layer for a planar heterojunction perovskite solar cell, the demonstrated memory property of PEDOT:PSS/MAPbI₃ combination opens up the application potential for multifunctional optoelectronic memory. The device is improved by introducing potassium iodide (KI) as an additive to ameliorate the quality of MAPbI₃ material and PEDOT:PSS/MAPbI₃ interface. As compared with the pristine MAPbI₃, the KI-doped perovskite device exhibits a resistive switching ON/OFF ratio of 10³, better endurance and more stable retention. The KI additive is helpful for forming uniform crystalline grain, high-compact structure and passivation of defect states for MAPbI₃ film and interface, which are the main reasons to the improved memory properties. Finally, we suggest that KI has great potential to be used as an additive for constructing a high performance perovskite memory device.