Halide Perovskite Nanocrystal‐Enabled Stabilization of Transition Metal Dichalcogenide Nanosheets

Abstract Transition metal dichalcogenide (TMD) nanosheets exfoliated in the liquid phase are of significant interest owing to their potential for scalable and flexible photoelectronic applications. Although various dispersants such as surfactants, oligomers, and polymers are used to obtain highly exfoliated TMD nanosheets, most of them are electrically insulating and need to be removed; otherwise, the photoelectric properties of the TMD nanosheets degrade. Here, inorganic halide perovskite nanocrystals (NCs) of CsPbX₃ (X = Cl, Br, or I) are presented as non‐destructive dispersants capable of dispersing TMD nanosheets in the liquid phase and enhancing the photodetection properties of the nanosheets, thus eliminating the need to remove the dispersant. MoSe₂ nanosheets dispersed in the liquid phase are adsorbed with CsPbCl₃ NCs. The CsPbCl₃ nanocrystals on MoSe₂ efficiently withdraw electrons from the nanosheets, and suppress the dark current of the MoSe₂ nanosheets, leading to flexible near‐infrared MoSe₂ photodetectors with a high ON/OFF photocurrent ratio and detectivity. Moreover, lanthanide ion‐doped CsPbCl₃ NCs enhance the ON/OFF current ratio to >10⁶. Meanwhile, the dispersion stability of the MoSe₂ nanosheets exfoliated with the perovskite NCs is sufficiently high.