Studies of Spin-Orbit Coupling strength in 2D and 3D organic/inorganic hybrid lead based perovskites by magnetic field effect

Organic/inorganic hybrid lead-based perovskites have been studied as advanced materials for novel optoelectronic devices.¹ In those materials, strong spin-orbit coupling (SOC) from lead atoms plays a decisive role in lowering the band gap and consolidating the optical absorption against the local distortions of the lattice, necessary for high performance solar cells.² Nevertheless, fundamental studies on SOC strength of these materials have still been very limited. Here, we present the magnetic field effect (MFE) in light emitting diodes (LEDs) made of the 3D hybrid perovskite CH₃NH₃PbI₃ (MAPbI₃) and 2D Ruddlesden-Popper hybrid perovskite (CH₃(CH₂)₃NH₃)₂(CH₃NH₃)Pb₂I₇, where the width and the magnitude of the magnetic response in conductivity and electroluminescence are measures of the SOC strength in the materials.³ We observed the magneto-conductance (MC) and magneto-electroluminescence (MEL) in the 3D perovskite devices in which MC and MEL with 0.07% magnitude and 250 G half width indicate the strong SOC strength. The absence of the MFE in the 2D perovskite devices indicates that the SOC strength is much larger due to the larger charge confinement effect in these materials.⁴ The results were confirmed by our MFE studies on the photocurrent of the devices.