Characterization of versatile syntheses for single crystal CH3NH3PbI3 perovskite nano structures

Abstract

Organic-inorganic hybrid perovskite materials such as methylammonium lead iodide (MAPbI3) and formamidinium lead iodide (FAPbI3) have gotten the spotlight as promising materials for optoelectronic applications due to low-cost material, solution processability and their peculiar optical and electrical properties. Many studies have been conducted to improve the efficiency of the device, and a lot of research has been under progress on stability, which is a further issue. Among the organometal halide perovskite, the organometal iodide perovskite is the most unstable materials. In recent years, many researchers have demonstrated that the optical properties of perovskite materials are largely dependent on their dimensions, thus, the ability to fully manipulate their dimensions will be vital for understanding the structure–property–device behavior relationship. Since low-dimensional perovskites are synthesized as a single crystalline state, they have a higher crystallinity than poly-crystals. So, they have excellent stability and device performance due to few defects and grain boundaries and exhibit a unique charge transport properties depending on their morphology. In addition, low-dimensional perovskites are more promising for future optoelectronic applications compared to bulk perovskites because they have unexpected optical and electrical properties from quantum size effects, large surface-to-volume ratio, and anisotropic geometry. Therefore, it is crucial for developing low-dimensional perovskite materials with various morphology. In this research, we have tried various synthesis methods for organic-inorganic hybrid perovskite single crystals with high crystallinity. Through the most commonly used method of reacting each precursor, lead iodide (PbI2) was first synthesized and then converted into perovskite by intercalating MA+ and I- within PbI2 layer. And among them, at room temperature without any other factors, we successfully devised a dipping method, a facile solution process capable of synthesizing low-dimensional perovskite single crystals, which can control morphology including nanoparticles, nanorods with a clear facet and nanoplates. Moreover, lead acetate (Pb(Ac)2) was used instead of the perovskite precursor PbI2, which was used as a backbone, to achieve the rapid growth of perovskite. And then the chemical and structural information of all synthesized perovskites was investigated using TEM. This result will provide an important role in enhancing device performance by improving material stability and extending device lifetime via a low cost, simple solution process.