The preparation and characterization of quasi-one-dimensional lead based perovskite CsPbI3 crystals from HI aqueous solutions

Quasi-one-dimensional lead based perovskite CsPbI3 exhibits increasing interests in quantum dots, solar cells, etc. However, high quality large CsPbI3 bulk crystals are still unexplored. Here we report CsPbI3 crystal growth from HI aqueous solution by tailoring the solubility. The morphology and crystal structure of CsPbI3 are characterized by SEM and XRD, which reveal the stick-like structure with the space group Pnma and lattice parameters a = 10.46 Å, b = 4.80 Å, and c = 17.78 Å. Ultra violet-visible transmission spectra substantiate CsPbI3 being a direct-gap semiconductor with a band-gap ∼2.69 eV. In addition, a broad emission at 550-580 nm with a large Stokes shift of 0.60 ∼ 0.75 eV and the corresponding dissociation energy 7.58 meV was found using temperature and power dependent PL spectra. This emission was attributed to a strong electron-phonon coupling induced “self-trap excitons” in CsPbI3. Our finding shields more light on the crystal growth, structure and optical properties of CsPbI3.