Modulating Nonlinear Optical Properties of (1R,2R)-DACHGeI₄ through Ce³⁺ Doping

Chiral perovskites exhibit great potential in polarization optics and spintronics due to their excellent structural and electronic properties. This study uses (1R,2R)-DACH as the organic component to synthesize a novel 2D germanium-based chiral perovskite single crystal, (1R,2R)-DACHGeI4 (where (1R,2R)-DACH is (1R,2R)-(−)-1,2-cyclohexanediamine). To address the impact of lattice defects in germanium-based perovskites on optical properties, a rare-earth Ce3+ doping compensation strategy is adopted. Experiments show Ce3+ doping enhances photoluminescence quantum yield and fluorescence lifetime, regulates spintronic states, replaces partial Ge2+ to cause lattice distortion, changes the crystal space group from chiral P21212 to nonchiral Pba2, and destroys the chiral structure. DFT calculations confirm these experimental results. This work provides a new approach to improving the nonlinear optical properties of 2D germanium-based perovskites and deepens the understanding of the intrinsic relationship between chiral perovskite structures and spintronic states.