**7. Conclusion**

Crystal structures of perovskite-type CH3NH3PbI3 compounds with cubic, tetragonal and orthorhombic structures were reviewed and summarized, and X-ray diffraction parameters and diffraction patterns were calculated and presented. Electron diffraction patterns were also calculated along various crystal directions and discussed. Other perovskite compounds such as CH3NH3PbCl3, CH3NH3PbBr3, CH3NH3GeCl3, CH3NH3SnCl3, and CsSnI3 were also re‐ viewed, which are expected as next generation, organic-inorganic hybrid solar cells with high photo-conversion efficiencies.
