Copper Doping Enables Superior Charge Separation for Enhanced Spin Coherence and CO₂ Photoreduction in CsPbBr₃ Quantum Dots

All-inorganic perovskite quantum dots have emerged as highly promising optoelectronic semiconductor nanomaterials, owing to their remarkable photoelectric properties. Herein, the copper ions were successfully doped into the CsPbBr₃ lattice, introducing a new trap state that facilitates rapid electron trapping and significantly enhancing room-temperature hole spin signals. In addition, photocharging dynamics were investigated using a prepump-pump-probe methodology, revealing three photocharged state lifetimes of 72 and 680 μs and >15 min in copper-doped CsPbBr₃ quantum dots (QDs), longer than that of the undoped ones. Furthermore, the copper-doped CsPbBr₃ QDs demonstrated superior photocatalytic activity for CO₂ reduction with an electron consumption rate of 72.3 μmol g^-1 h^-1, nearly 1.9 times higher than that of undoped CsPbBr₃ QDs, due to the long-lived photocharged states. These findings unveil the pivotal role of dopant-mediated trap states in controlling spin coherence and charge dynamics, offering a versatile design framework for developing multifunctional perovskite QDs for spin-based optoelectronics and photocatalysis.