Nonlayered two-dimensional (2D) β-In2S3 nanostructures have demonstrated outstanding electronic and optoelectronic properties, which requires its large-scale single-crystalline films to suppress carrier scattering. However, the weak energy for In−S chemical bonds and inherent nonlayered structure with three dimensional bonds make it highly challenging to achieve large area 2D β-In2S3 nanoflakes, which is still limited by the high nucleation density and three-dimensional isotropic growth tendency. Herein, we propose a universal strategy of suppressing nucleation and slow-kinetic epitaxial growth of large domain 2D nonlayered β-In2S3 nanoflakes via water molecules for the optoelectronic applications. The water molecules acted as the function of partially oxidized In2S3 nucleus via mild oxidation, which reduced the nucleation density by approximately three orders of magnitude and enabled the formation of large-area single-crystal with an average domain size of 120 μm and a maximum size approaching 270 μm. The structural characteristics and electronic structures of our β-In2S3 samples characterized by various characterization techniques showed unique single-crystalline nature and modified Fermi level properties. Furthermore, the diverse nanostructures of β-In2S3 could be precisely tuned from triangular nanosheets to nanowires by controlling the growth conditions. The two-terminal β-In2S3 photodetectors exhibited excellent performance with a high photoresponsivity of 44 A·W−1 and a fast response speed with rise and decay times of 6 and 7 ms, respectively, revealing the superior physical properties of large domain 2D β-In2S3. This work provides a universal water-assisted strategy for synthesizing large-area 2D non-layered materials and paves the way for significant potential of high-quality large-scale single-crystalline β-In2S3 for advanced optoelectronic devices applications.
He et al. (Thu,) studied this question.