Memory Devices via Unipolar Resistive Switching in Symmetric Organic–Inorganic Perovskite Nanoscale Heterolayers

Abstract

Organic–inorganic hybrid perovskite thin films with nanostructured polycrystalline grains have shown great potential in various nanoscale optoelectrical applications. Among them, the field of electrical memory has fallen behind due to insufficient knowledge of the related resistive switching characters and mechanisms. In the present work, switching behaviors of perovskite memory devices are systematically analyzed by comparing them with organic memory devices. We found that decreasing the conductivity of a polycrystalline perovskite thin layer would lead to unipolar switching behaviors, which is supplementary to the present perovskite memory family where bipolar switching is commonly reported. Moreover, our proposed symmetrical device with a nanoscale heterolayer structure enables us not only to achieve highly reproducible unipolar switching devices but also to settle the argument whether microconducting channels exist within perovskite memory devices through characterizing the microscopic morphological homogeneity. Surprisingly, the scanning electron microscopy results show that partial 10 μm large perovskite grains would be decomposed into various 100 nm small grains under high external bias, indicating the presence of microconducting channels. Furthermore, energy-dispersive X-ray spectroscopy results together with photoluminescence results of the perovskite thin film before and after applying bias are nearly identical, demonstrating that microconducting channels are formed without any difference in compositions or optical properties. Our discoveries provide a practical strategy to achieve electrical storage via organic–inorganic hybrid perovskite thin-film devices.

Revealing Charge Transfer Dynamics in Methylammonium Lead Bromide Perovskites via Transient Photoluminescence Characterization

“…Moreover, EQE can still maintain >1% when the current density is as high as 600 mA/cm 2 . The turn-on voltage of our device is around 2.9 V. As for the “jump” at around 1 V in the I – V curve, and we attributed it to the unexpected microconducting channels, which has been reported in our previous work . Interestingly, the EL emission spectrum in Figure c shows only one peak at 546 nm with a full width at half maximum (FWHM) of 19.3 nm.…”

“…The turn-on voltage of our device is around 2.9 V. As for the "jump" at around 1 V in the I−V curve, and we attributed it to the unexpected microconducting channels, which has been reported in our previous work. 45 Interestingly, the EL emission spectrum in Figure 3c shows only one peak at 546 nm with a full width at half maximum (FWHM) of 19.3 nm. It indicates that only large grains emit light under the condition of carrier injection only.…”

Vibrational study of lead bromide perovskite materials with variable cations based on Raman spectroscopy and density functional theory

“…[1][2][3][4][5][6] Over the past decades the MHPs have emerged as suitable materials for solar cells, light emitting diodes, lasers, transistors, and memory devices. [7][8][9][10][11][12][13] It has been demonstrated that MHP-based photovoltaic devices show power conversion efficiencies of more than 22%, [14,15] and the devices can be produced on cheap non-crystalline substrates by both vapor deposition and solution processing. [8,11,16,17] Their excellent performance originates from the outstanding optoelectronic properties such as direct band-to-band recombination, long exciton diffusion length, high absorption coefficient.…”

Low‐Dimensional Metal‐Halide Perovskites as High‐Performance Materials for Memory Applications

“…3D halide perovskites are the earliest and most commonly studied ones in the RS memory field since 2015. [69] So far, 3D perovskites have achieved extraordinary performance in memory applications, including a high ON/OFF ratio of 10 9 , [70] a small set/reset voltage of 0.1 V, [22] and a long retention time of over 10 5 s. [71,72] Unipolar, [73] bipolar, [74] and writeonce-read-many times (WORM) [75] switching types have been realized. Besides, due to their intrinsic photo-sensitive nature, 3D perovskites have been utilized in photonic memristors, which simultaneously respond to light illumination as another external stimulus in addition to the conventional electric bias.…”