Iodine Vacancy Redistribution in Organic–Inorganic Halide Perovskite Films and Resistive Switching Effects

Abstract

Organic-inorganic halide perovskite (OHP) materials, for example, CH NH PbI (MAPbI ), have attracted significant interest for applications such as solar cells, photodectors, light-emitting diodes, and lasers. Previous studies have shown that charged defects can migrate in perovskites under an electric field and/or light illumination, potentially preventing these devices from practical applications. Understanding and control of the defect generation and movement will not only lead to more stable devices but also new device concepts. Here, it is shown that the formation/annihilation of iodine vacancies (V 's) in MAPbI films, driven by electric fields and light illumination, can induce pronounced resistive switching effects. Due to a low diffusion energy barrier (≈0.17 eV), the V 's can readily drift under an electric field, and spontaneously diffuse with a concentration gradient. It is shown that the V diffusion process can be suppressed by controlling the affinity of the contact electrode material to I ions, or by light illumination. An electrical-write and optical-erase memory element is further demonstrated by coupling ion migration with electric fields and light illumination. These results provide guidance toward improved stability and performance of perovskite-based optoelectronic systems, and can lead to the development of solid-state devices that couple ionics, electronics, and optics.

Nanoionic Resistive‐Switching Devices

“…[42,43] Several recent studies have also started to explore controlled ion migrations in materials such as organic-inorganic halides (e.g., CH 3 NH 3 PbI 3 ), [44] which have attracted broad interest as a promising optoelectronic material for solar cell, [45] photodetector, [46] light-emitting diodes, [47] and laser [48] applications. [49] Moreover, more iodine vacancies were observed near the cathode, indicating the growth of iodine vacancy filaments was initiated from the cathode and extended to the anode. For example, in the Ag/CH 3 NH 3 PbI 3 /Ag RS system (Figure 2f), it was shown that the I:Pb atomic ratio in the CH 3 NH 3 PbI 3 film can be significantly decreased at LRS, then partially restored at HRS.…”

“…Sulfur vacancy-induced doping effect has also been used by Sangwan et al to explain the RS effect in devices based on chemical-vapor-deposition-(CVD)grown monolayer MoS 2 film. [49] Copyright 2017, John Wiley & Sons, Inc. i) Schematic illustration of a few-layer MoS 2 device with Ti/Au electrodes. [32] Copyright 2010, Springer Nature.…”

Recent Advances in Memory Devices with Hybrid Materials

“…Recently, Guan et al suggested that migration of MA vacancies in the layer and modulation of the Schottky barrier at the perovskite/ITO interface may also contribute to resistive switching in OIPbased memory. [49] Copyright 2017, John Wiley & Sons. The MAPbBr 3 and ITO bottom electrode formed a Schottky junction.…”

“…[42][43][44][45] However, OIP-based photovoltaic device exhibits difference in current-voltage curve (hysteresis) under forward and reverse scanning directions which is undesirable in optoelectronic applications. [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] Moreover, OIPs are photosensitive, and this trait can be exploited in device with photon recording functionality. [47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] Moreover, OIPs are photosensitive, and this trait can be exploited in device with photon recording functionality.…”

Memristors with organic‐inorganic halide perovskites

“…Unlike these materials, OHPs benefit considerably from their mixed ionic‐electronic conduction behavior, that is, the halide counterions of OHPs are mobile under an electric field . In particular, novel unique functions can be developed with OHP‐based memristors that take advantage of the remarkable photoabsorption ability of this emerging material system through synergistic coupling of photonic, electronic, and ionic processes …”