Abstract
Methylammonium lead halide perovskites have attracted extensive attention for optoelectronic applications. Carrier transport in perovskites is obscured by vacancy-mediated ion migration, resulting in anomalous electronic behavior and deteriorated reliability of the devices. In this communication, we demonstrate that ion migration can be significantly enhanced by doping additional mobile I- ions into the perovskite bulk. Ionic confinement structures of vertical metal oxide semiconductor (MOS) and lateral metal semiconductor metal (MSM) diodes designed to decouple ion-migration/accumulation and electronic transport are fabricated and characterized. Measurement conditions (electric-field history, scan rate and sweep frequency) are shown to affect the electronic transport in perovskite films, through a mechanism involving ion migration and accumulation at the block interfaces. Prominent zero-point drifts of dark current-voltage curves in both vertical and lateral diode are presented, and further varied with the perovskite film containingthe different iodine-lead atomic ratio. The doped perovskite has a large ion current at grain boundaries, offering a large ion hysteresis loopand zero drift value. The results confirmthat the intrinsic behavior of perovskite film is responsible for the hysteresisof the optoelectronic devices, but also paves the way for potential applications in many types of devices including memristors and solid electrolyte batteries by doping the native species (I− ions) in perovskite film.
Highlights
In the past decade, solar cells (PSCs) based on hybrid organic-inorganic perovskites and other optoelectronic devices have made great progress [1,2,3,4].These achievements are attributed to the distinguished optoelectronic properties of perovskites, such as high photoelectric conversion efficiencies, low radiation, high charge carrier mobility, high gain, and mixed ionic-electronic conductivity [2,5,6,7,8,9,10]
To understand the effect of iodine doping on the growth and crystallization of perovskite films, the surface topography and the crystalline characteristics were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD) patterns
We demonstrated the effect of doping properties on the hysteresis loop and zero by doping the native species onto the CH3 NH3 PbI3 perovskite
Summary
Solar cells (PSCs) based on hybrid organic-inorganic perovskites and other optoelectronic devices have made great progress [1,2,3,4].These achievements are attributed to the distinguished optoelectronic properties of perovskites, such as high photoelectric conversion efficiencies, low radiation, high charge carrier mobility, high gain, and mixed ionic-electronic conductivity [2,5,6,7,8,9,10]. There is currently no universally accepted mechanism that can explain this phenomenon unanimously, the research done so far has provided a deeper understanding of the subject. It is accepted by most researchers that current hysteresis may be an intrinsic property of perovskite materials that may originate from the Materials 2018, 11, 1606; doi:10.3390/ma11091606 www.mdpi.com/journal/materials. The diffusion of intrinsic ion defects in organometal halide perovskites has an important influence on the performance of perovskite devices [9,12,17,20,21,22,23].
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