Brightening of Dark States in CsPbBr₃ Quantum Dots Caused by Light‐Induced Magnetism

Abstract Lead halide perovskite quantum dots (QDs) have shown great potential for optoelectronic and quantum photonic applications. Although controversy remains about the electronic fine structures of bulk perovskites due to the strong spin‐orbit coupling affecting the conduction bands, compelling evidence indicates that the ground states of perovskite QDs remain dark, limiting their applications in optoelectronic devices. Here, it is demonstrated that photoexcitation can induce large intrinsic magnetic fields in Mn‐doped CsPbBr₃ perovskite QDs. Equivalent to applying an external magnetic field, the light‐induced field causes giant Zeeman splitting to the bright triplet states and brightens the dark singlet ground state, thus effectively rendering a partially bright ground state in the doped QDs. These findings here may contribute to the understanding of the electronic fine structures in perovskite QDs and demonstrate a potential approach for creating semiconductor nanostructures that can serve as bright light sources.