Water‐Durable Cesium Lead Halide Perovskite Nanocrystals Passivated with a Cationic Gemini Surfactant

Abstract Chemical states of perovskite nanocrystal surfaces are vital to withdraw their intrinsic optoelectronic nature and maintain the colloidal stability. This study reports that the cationic gemini surfactant alkanediyl‐α,ω‐bis(dodecyldimethylammonium bromide) “12‐ n ‐12” dramatically improved the luminescence properties and chemical stability of cesium lead bromide nanocrystals (CsPbBr 3 NCs). Dispersion stability of CsPbBr 3 NCs passivated with 12‐ n ‐12 ( n = 3−7) is enhanced with the methylene spacer length, their dynamic light scattering studies ensure that the gemini ligands with more than the pentyl methylene spacer exhibit mono dispersion of NCs. Nuclear magnetic resonance and X‐ray photoemission spectroscopy studies reveal that 12‐ n ‐12 is bound to the surfaces of CsPbBr 3 NCs with a density of 0.74−1.06 nm −2 which is less than half the didodecyldimethylammonium bromide (DDAB) ligand density. Nevertheless, CsPbBr 3 NCs with the 12‐ n ‐12 shell exhibit a high photoluminescence quantum yield equal to that of DDAB. Furthermore, the 12‐ n ‐12 shell demonstrates remarkably excellent luminescence stability when the NC solution is exposed to water. Hence, 12‐ n ‐12 is a promising candidate to substitute the conventional ligands.