Identifying Photoinduced Dipolar Polarization and Orbit–Orbit Interaction between Excitons in Organic–Inorganic Hybrid Perovskites

Abstract

Photoinduced polarization and orbit-orbit interaction are important issues in hybrid perovskites toward developing optoelectronic functionalities. This paper identifies that photoinduced polarization occurs in hybrid perovskites with mixed-cation methylammonium (MA)/formamidinium (FA) (MA x FA (1−x) PbI 3) by measuring bulk polarization at 1 MHz in a magnetic field. Interestingly, when the internal dipole moment is increased upon increasing the MA:FA ratio, the photoinduced dipolar polarization can be substantially enhanced, clarifying the controversial issue of whether photoexcitation can induce a dielectric polarization within dipolar polarization regime in hybrid perovskites. Furthermore, upon increasing photoinduced dipolar polarization, it is found that the intrinsic orbit-orbit interaction between excitons can be increased, revealed by monitoring photocurrent change (ΔJ sc) upon switching the photoexcitation between linear and circular polarizations. This presents that organic cations are directly involved in the orbit-orbit interaction within band structures. Clearly, the studies provide an insightful understanding of the dipole moment effects on photoinduced dipolar polarization and orbit-orbit interaction between excitons in hybrid perovskites toward controlling the optoelectronic properties.

Understanding the Mechanism of PbCl2 Additive for MAPbI3‐Based Perovskite Solar Cells

“…The rate of incremental variation of photogenerated charge carriers reflects the charge transport efficiency across solar cell devices, which indicates that localized electron polarization is enhanced via additive engineering. [ 33,34 ] In conclusion, the C – V results appeared to be consistent with the AFM measurements.…”

Room‐Temperature Magnetic Field Effect on Excitonic Photoluminescence in Perovskite Nanocrystals

“…In fact, local site symmetry breaking occurs for CPCBM, which indicates a stronger SOC that often resists the magnetic field effect by spin scattering. [4,37] Therefore, there must be an orbital effect which is triggered by external magnetic field which can effectively enhance the MFE. [37,38] The ordering of orbital magnetic dipoles occurs specifically for electrons in the excited states, which could generate an orbital field with the organization energy of at least 26 meV (300 K) to induce the room-temperature MFE.…”

“…[4,37] Therefore, there must be an orbital effect which is triggered by external magnetic field which can effectively enhance the MFE. [37,38] The ordering of orbital magnetic dipoles occurs specifically for electrons in the excited states, which could generate an orbital field with the organization energy of at least 26 meV (300 K) to induce the room-temperature MFE. This scenario could be comparably studied by the T-dependent Mn-PL intensities, as shown in Figure 3d.…”

Spinterfaces Manipulate Large Magnetic Field Effects in 3D and Quasi‐2D Organic–Inorganic Hybrid Perovskites

“…Importantly, they were applied for revealing the internal spin dynamics at excited states for OIHPbased solar cells and light emitting devices. [15,16,23,24] On the other hand, an intriguing question may arise, to which extend, MFEs can be affected by ferromagnetic electrodes and the ferromagnet/perovskite spinterfaces.…”

“…Importantly, they were applied for revealing the internal spin dynamics at excited states for OIHPbased solar cells and light emitting devices. [15,16,23,24] On the other hand, an intriguing question may arise, to which extend, MFEs can be affected by ferromagnetic electrodes and the ferromagnet/perovskite spinterfaces.Herein, we have fabricated prototypical perovskite spin valves (PeSVs) with vertical structures comprising Ni/MAPbI 3−x Cl x / Ni and Ni/(PEA) 2 (MA) 3 Pb 4 I 13 /Ni. Both MAPbI 3−x Cl x and (PEA) 2 (MA) 3 Pb 4 I 13 are chemically processed based on our early experiences.…”