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We systematically synthesized CH 3 NH 3 PbI 3 crystals using solvothermal process, and the reaction conditions such as concentration of the precursor, temperature, time, and lead source have been comprehensively investigated to obtain shape-controlled CH 3 NH 3 PbI 3 crystals. The results showed that the CH 3 NH 3 PbI 3 crystals exhibit tetragonal phase and the crystals change from nanoparticles to hopper-faced cuboids. Photoluminescence spectra of the crystals obtained with different lead sources show a blue shift due to the presence of defects in the crystals, and the peak intensity is very sensitive to the lead sources. Moreover, impurities (undesirable byproducts and excess components like HI or CH 3 NH 2 ) presented during crystal growth can result in hopper growth.

Lead sulfide (PbS) with multi-morphologies were synthesized via solvothermal route under the assistance of l -cysteine. Reaction conditions such as concentration of l -cysteine, reacting temperature, reacting time and solvents have been systemically investigated in order to obtain shape-controlled PbS micro-crystals. A series of morphologies, such as cubic, Dendritic Hierarchical, Octagonal Hierarchical flowerlike and Vertebration shapes were obtained successfully. Self-assembly and a hypothesis based on Boltzmann distribution were introduced for illustration of morphology evolution obtained under different reacting temperatures, and the effect of the solvents and the role of l -cysteine were also discussed in detail. To testify the effects of different morphologies on the optical properties of PbS, the absorption spectra of some samples were measured. These results demonstrated that our work offers an effective way to develop the tunable synthesis of multi-shaped PbS for various applications.