Studies Of Circularly Polarized Luminescence In Perovskite Films

Hybrid organic–inorganic perovskites(HOP)have both strong spin-orbit interactions and long electron spin lifetimes,making them an important material for the study of spintronics.Studies of the unique spin-related optoelectronic properties of HOP,such as magneto-optical effect,polarized light-related effects,especially the photoemission properties of circularly polarized light excitation,combined with the measurement of material properties,experimental methods of optical injection of spins,and optical modulation of electron spin states will be obtained.In addition,perovskite solar cells have developed rapidly in recent years,with efficiency over 25%.Due to its higher band gap and stability,MAPb Br₃ can provide some new ideas for the development of solar cells.This theis focuses on the study of the following:(1)Circularly polarized luminescence and polarizability study of 3D perovskite MAPb Br₃:It is found that resonant excitation is favorable to obtain higher polarization rate.The scattering of excitons and defects leads to a slow change of polarization rate,and the phase transition triggers an abrupt change of polarization rate.Compared with MAPb Br₃,the larger spin-orbit coupling(SOC)in MAPb I₃ accelerates the process of polarization recession.(2)Study of circularly polarized luminescence and polarizability of quasi-2D perovskite(C₆H₅C₂H₄NH₃)₂(MA)_n-1Pb_nBr_3n+1[(PEA)₂(MA)_n-1Pb_nBr_3n+1]:characterization of thin film samples inferred that excitons are the dominant photoexcited state of the film at low temperatures.Strong exciton-phonon interactions exist in the two-dimensional material and change with the number of inorganic layers n.Defects reduce the process of polarization recession by binding excitons to carriers.(3)Performance study of the MAPb Br₃,MAPb I₃ and(PEA)₂(MA)_n-1Pb_nBr_3n+1 perovskite solar cells:band gap will directly affect a variety of cell performance.Wider band gap in MAPb Br₃ is beneficial to increase the V_OC.MAPb Br₃ can provide higher stability than MAPb I₃.Optimization of perovskite films as light-absorbing materials can effectively improve the parasitic resistance of the cell and enhance performance.Traditional metal electrodes have a negative impact on the cell lifetime.