Tailoring Interfacial Electron Transfer in Au/S‐Cs 2 SnI 6 @Liquid Crystal Heterostructures for Enhanced Nonlinear Optical Property
Jiaqi Qi, Xuanfeng He, Haitao Jiang, Yuhuai Fei, Yinying Cheng, Jing Song, Cong Wang, Donglai HanABSTRACT
Tin‐based perovskites are promising lead‐free candidates for nonlinear optical applications, yet their performance and stability require further improvement. This work proposes a multi‐step interface engineering strategy to markedly enhance the nonlinear optical response. A stable Cs 2 SnI 6 (S‐Cs 2 SnI 6 ) film was first prepared via an improved in situ growth method, exhibiting an initial nonlinear absorption coefficient ( β ) of −4.12 × 10 −7 m W −1 . By replacing the conventional liquid crystal 4‐Cyano‐4’‐pentylbiphenyl (5CB) with the π ‐conjugated liquid crystal 4‐[(4‐Pentylphenyl)iminomethyl]benzonitrile (5CNB), an S‐Cs 2 SnI 6 @5CNB composite was obtained. The optimized interfacial interaction facilitated electron transfer, resulting in a significantly enhanced β value of 2.05 × 10 −6 m W −1 . Further incorporation of plasmonic gold nanoparticles (Au NPs) yielded the Au/S‐Cs 2 SnI 6 @5CNB heterostructure. Benefiting from the localized surface plasmon resonance (LSPR) of Au NPs, the local electromagnetic field was substantially intensified, boosting β value to 6.94 × 10 −6 m W −1 , a 239% increase over the composite without Au and a 434% increase over the control without the perovskite. Z‐scan measurements confirmed outstanding optical limiting with a low threshold of 0.072 J cm −2 . This study successfully demonstrates a synergistic enhancement strategy, paving the way for advanced optical limiters and nonlinear photonic devices.