Optical Absorption Coefficient Red Shift Effect Of Iodine Vacancy In Mapbi(3)

The Density Function Theory with van der Waals correction are employed to investigate the materials of CH3NH3PbI3 (MAPbI(3)). For the two phases of tetragonal and orthorhombic, the high optical absorption coefficients (OAC) result from electrons jumping from I 5p to the Pb 6p near the Fermi level. The two different kinds of iodine vacancy result in the doping energy band appearing in the band gap, and the doping energy band is from Pb 6p electrons mainly, which is below the Fermi level. The iodine vacancy result in the red shift of OAC, which result in the optical absorption of MAPbI(3) with the iodine vacancy locating in the range from 0.5 eV to 1.47 eV, which locate at the infrared ray part occupying 51% of radiant energy of sunlight. And the red shift favors power transfer between sunlight and electric. The red shift of the OAC originate electrons jumping from Pb 6p (doping energy bands) to Pb 6p (conduction bands).