Nonlinear Optical Properties of Cs₂AgIn_1-BiCl₆ Single Crystals

Lead-free double perovskites offer enhanced stability and lower toxicity compared to their lead-based counterparts. Dual B-site cations can introduce elemental and structural diversity into double perovskite materials, enabling fine-tuning of the optical properties. However, the study of the nonlinear optical (NLO) properties of lead-free double perovskites is still nascent, hindering their relevant potential applications. Based on this, this work synthesizes a series of Cs₂AgIn_1-BiCl₆ (x = 0, 0.1, 0.25, 0.75, 1) single crystals, with the aim to explore the impact of composition on their NLO properties. Interestingly, Cs₂AgInCl₆ shows surface defect-induced second harmonic generation. With increasing Bi³⁺ concentration, the multiphoton absorption coefficients of Cs₂AgIn_1-BiCl₆ single crystals increase as a result of increasing state density. This work is helpful to understand well the NLO properties of lead-free double perovskites, laying a foundation for the development of related applications.