Light-induced Kondo-like exciton-spin interaction in neodymium(II) doped hybrid perovskite.

Tuning the properties of a pair of entangled electron and hole in a light-induced exciton is a fundamentally intriguing inquiry for quantum science. Here, using semiconducting hybrid perovskite as an exploratory platform, we discover that Nd ²⁺ -doped CH ₃ NH ₃ PbI ₃ (MAPbI ₃ ) perovskite exhibits a Kondo-like exciton-spin interaction under cryogenic and photoexcitation conditions. The feedback to such interaction between excitons in perovskite and the localized spins in Nd ²⁺ is observed as notably prolonged carrier lifetimes measured by time-resolved photoluminescence, ~10 times to that of pristine MAPbI ₃ without Nd ²⁺ dopant. From a mechanistic standpoint, such extended charge separation states are the consequence of the trap state enabled by the antiferromagnetic exchange interaction between the light-induced exciton and the localized 4 f spins of the Nd ²⁺ in the proximity. Importantly, this Kondo-like exciton-spin interaction can be modulated by either increasing Nd ²⁺ doping concentration that enhances the coupling between the exciton and Nd ²⁺ 4 f spins as evidenced by elongated carrier lifetime, or by using an external magnetic field that can nullify the spin-dependent exchange interaction therein due to the unified orientations of Nd ²⁺ spin angular momentum, thereby leading to exciton recombination at the dynamics comparable to pristine MAPbI ₃ .
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