Unraveling the origin of resistive switching behavior in organolead halide perovskite based memory devices

This study investigates the operation mechanisms of organolead halide perovskite based resistive memory cells and explores the device architectures that could ensure high memory endurance and high fabrication reproducibility. By introducing thin polyethyleneimine (PEI) interfacial layers to separate the direct contact of the perovskite layer with the top and bottom electrodes, thus producing a device structure of ITO/PEI/CH3NH3PbI3/PEI/metal, we achieved endurance cycles of more than 4000 times while maintaining a low operation voltage around 0.25 V. Furthermore, reproducible memory switching behavior was demonstrated among 180 devices fabricated from eight different device batches. To study the memory mechanism, we varied the top electrode (TE) metal materials and found three distinctively different resistive switching characteristics for InGa, Ag, and Al electrodes, respectively. The results suggest that the memory switching originates from a concerted effect of defect motion in the perovskite film and metal ion diffusion from the TE and that the switching mechanism is associated with the substitutionality of the metal ion in the Pb–I cage. For Ag ions with high substitutionality, the memory turn-on is dominated by interface vacancies, whereas for Al ions with low substitutionality, filament formation governs the memory switching.