Incorporation of Cesium Ions into MA(1-x)Cs(x)Pbl(3) Single Crystals: Crystal Growth, Enhancement of Stability, and Optoelectronic Properties

Organic-inorganic hybrid methylammonium lead iodide perovskite (MAPbI(3)) has attracted extensive attention in a series of optoelectronic devices. The photoelectric properties of the MAPbI(3) single crystal have been revealed to be much better than those of it polycrystalline counterparts. However, its poor moisture and heat resistance severely limited further development. The introduction of Cs+ into polycrystalline films has shown to be an effective way to enhance its moisture resistance through a passivation effect. However, the entrance abilities of Cs+ into a MAPbI(3) crystal lattice and the influence on photoelectric properties of a single crystal were not clear until now. Therefore, we attempted to grow large MA(1-x )Cs(x)PbI(3) single crystals to introduce Cs(+ )into the crystal lattice. The existence of Cs+ brought lattice shrinkage and enhanced stability of the MAPbI(3) single crystal. A moderate quantity of Cs+ (2%) proved to heighten the photoelectric properties, whereas an excess quantity of Cs+ (5%) brought more shallow defects, which ultimately deteriorated the photoelectric properties.