Preparation of In2S3 and Cu-Doped In2S3 2D Ultrathin Nanoflakes with Tunable Absorption and Intense Photocurrent Response

We reported an effective method to synthesize In₂S₃ and Cu-doped In₂S₃ two-dimensional ultrathin nanoflakes by the hydrothermal method through tuning the Cu/In molar ratio. The transmission electron microscope images showed that the products had ultrathin flake-like shape with wrinkling and rolling. The X-ray diffraction patterns indicated the crystal phase of nanoflakes was varied from β-In₂S₃ to tetragonal-CuInS₂ as the Cu/In molar ratio was increased. The In₂S₃ nanoflakes exhibited absorption band at 450 nm, while new absorption peaks in turn appeared at 550 nm and 670 nm as the Cu/In molar ratio was increased. In addition, the two-dimensional ultrathin nanoflakes exhibited intense photocurrent response.