Copper Doping Enables Superior Charge Separation for Enhanced Spin Coherence and CO₂Photoreduction in CsPbBr₃Quantum 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 CsPbBr₃lattice, 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 CsPbBr₃quantum dots (QDs), longer than that of the undoped ones. Furthermore, the copper-doped CsPbBr₃QDs demonstrated superior photocatalytic activity for CO₂reduction with an electron consumption rate of 72.3 μmol g^–1h^–1, nearly 1.9 times higher than that of undoped CsPbBr₃QDs, 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.