Chiral Quantum-Cutting

Near-infrared circularly polarized luminescence (NIR-CPL) holds great promise for advanced photonic applications, however, simultaneously achieving both high photoluminescence quantum yield (PLQY) and large asymmetry factor (glum) in the NIR region remains challenging owing to the energy-gap law. Herein, we propose a chiral quantum-cutting strategy based on rare-earth ion-doped chiral perovskite quantum dots (PeQDs). Specifically, the obtained chiral PeQDs exhibit strong NIR-CPL at 985 nm with both a large glum of 0.092 and high PLQY of 157.2%, resulting in an exceptional figure of merit (FM = |glum| × PLQY) of 0.145, representing the highest value among the reported chiral perovskites. The femtosecond-transient absorption spectra confirmed an ultrafast energy transfer accompanied by efficient spin preservation owing to the chirality-induced spin selectivity (CISS) effect, which resulted in the imbalanced spin population of Yb3+ ions and enabled efficient NIR-CPL. Therefore, for the first time, we proposed and demonstrated the concept of chiral quantum-cutting effect and revealed the mechanism of spin flip and preservation during energy and chirality transfer based on the CISS effect. Our work provides a novel strategy for designing efficient NIR-CPL materials with large glum and high PLQY, opening new avenues for developing high-performance chiral optoelectronic and spintronic devices in the NIR region.