Ferromagnetic and Antiferromagnetic Properties of Perovskite Solar Cell Materials

Abstract

This paper provides an intriguing electronic and magnetic properties of the Perovskite solar cell materials (MAPbI3, CsGeI3) which are analyzed by using density functional theory, where MAPbI3 is the abbreviation of CH3NH3PbI3. Herein, we mainly discuss the influence of ferromagnetism and antiferromagnetism on the crystal structure, band gap and electronic density of states of perovskite (MAPbI3) (CsGeI3). The magmom values of the applied magnetic field are from −6 μB to 6 μB, respectively (The negative sign here represents the opposite direction of the original magnetic field). The lattice parameters and volume of the crystal under different magnetic fields are obtained. It can be seen from the free energy that the stability of the crystal is compared with non-magnetic field, when the applied magnetic fields are at 4 μB and 5 μB, the free energy of the crystal is the lowest and its relative stability is better. At the same time, the magnetic field of CsGeI3 increases from −5 μB to 5 μB. The results show that the density of states of CsGeI3 moves towards the direction of higher energy, and the change of MAPbI3 crystal is more obvious. Similarly, we should pay attention to that when applying a magnetic field to the crystals, it is found that the band gap of both MAPbI3 and CsGeI3 decreases obviously after increasing the magnetic field, which avoids the situation of spin up and spin down overlap of MAPbI3, which is helpful to adjust the band gap size. From the perspective of crystal spectral absorption characteristics, when considering the ferromagnetic effect on CsGeI3 with the magnetic moment of a single atom is set to (1 μB, 2 μB, 3 μB, 4 μB, 5 μB, 6 μB), the width of absorption spectrum tends to decrease, but the impact on MAPbI3 is small.