The study of electronic and optical properties of perovskites CH3NH3PbCl3 and CH3NH3PbBr3 using first-principleLhouceine Moulaoui, Omar Bajjou, Abdelhafid Najim and Khalid RahmaniE3S Web Conf., 336 (2022) 00015DOI: https://doi.org/10.1051/e3sconf/202233600015