Modulating Nonlinear Optical Properties of (1<i>R</i>,2<i>R</i>)-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 (1<i>R</i>,2<i>R</i>)-DACH as the organic component to synthesize a novel 2D germanium-based chiral perovskite single crystal, (1<i>R</i>,2<i>R</i>)-DACHGeI₄ (where (1<i>R</i>,2<i>R</i>)-DACH is (1<i>R</i>,2<i>R</i>)-(-)-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 <i>P</i>2₁2₁2 to nonchiral <i>Pba</i>2, 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.