Dynamic Electronic Junctions in Organic–Inorganic Hybrid Perovskites

Abstract

Organic-inorganic hybrid perovskites have shown great potential as building blocks for low-cost optoelectronics for their exceptional optical and electrical properties. Despite the remarkable progress in device demonstration, fundamental understanding of the physical processes in halide perovskites remains limited, especially the unusual electronic behaviors such as the current-voltage hysteresis and the switchable photovoltaic effect. These phenomena are of particular interests for being closely related to device functionalities and performance. In this work, a microscopic picture of electric fields in halide perovskite thin films was obtained using scanning laser microscopy. Unlike conventional semiconductors, distribution of the built-in electric fields in the halide perovskite evolves dynamically under the stimulation of external biases. The observations can be well explained using a model based on field-assisted ion migration, indicating that the mechanism responsible for the evolving charge transport observed in this material is not purely electronic. The anomalous dynamic responses to the applied bias are found to be effectively suppressed by operating the devices at reduced temperature or processing the materials at elevated temperature, which provide potential strategies for designing and creating halide perovskites with more stable charge transport properties in the development of viable perovskite-based optoelectronics.

Ion Migration: A “Double‐Edged Sword” for Halide‐Perovskite‐Based Electronic Devices

“…Moreover, ion migration has found important application in perovskite resistance‐switching memory devices . Finally, by manipulating the ion migration progress under different electric field, dynamic electronic junctions are demonstrated and can be used as fast response photodetectors . Therefore, understanding and manipulating of the ion migration process in HOIP materials, which has been a formidable challenge, holds the key for developing “state of the art” perovskite devices.…”

Strong Depletion in Hybrid Perovskite p–n Junctions Induced by Local Electronic Doping

“…One should also note here that the perovskite p-n junctions formed by surface electronic doping are fundamentally different from those depending on electrical poling, in which perovskite crystal changes in terms of defect level, lattice constant, and bandgap. [48,49] Figure 4a shows a schematic of a lateral perovskite nanosheet p-n junction diode. The For instance, a photocurrent of ~0.19 nA is measured at +1 V, which is much larger than the photocurrent of ~0.064 nA at −1 V. Importantly, the photocurrent of the p-n diode is over 3 times that of the pristine perovskite device (~0.059 nA at +1 V).…”

“…properties, the application of the electrical bias (~1 V) in both the pristine perovskite device and the perovskite photodiode could induce the migration of CH 3 NH 3 + and Iions and then influence the distribution of the local electric field. [49] This in turn leads to an unusual photocurrent characteristics in the as-fabricated perovskite photodiode.…”

Electric-Field-Induced Dynamic Electronic Junctions in Hybrid Organic–Inorganic Perovskites for Optoelectronic Applications

“…The migration of ions can be considered as dynamic doping, and thus it is anticipated that dynamic electronic junctions could be created by controlling the migration of ions under the applied external electric field. 37 The output ( I vs V ) curves of the devices exhibit dependence on the history of applied biases (Figure 1d). The I – V curve without poling under white light (1.4 mW/cm 2 ) illumination indicates that the contact between perovskite and Au is not perfectly Ohmic (or Ohmic-like).…”