Deciphering the Carrier Transport Properties in Two-Dimensional Perovskites via Surface-Enhanced Raman Scattering.

2D layered organic-inorganic perovskites have attracted substantial attention due to their high stability and promising optoelectronic properties. However, in-depth insights on the anisotropic carrier transport properties of these 2D perovskites are remaining challenging, while they are significant for further designing the high-performance device applications. Here, the carrier transport properties within 2D perovskite single crystals are investigated and a layered-carrier-transport model is developed through the non-invasive and non-destructive surface-enhanced Raman scattering techniques. The carrier transport features of 2D perovskites show clearly the thickness-, applied voltage- and anisotropy-dependent behaviors, which are demonstrated to origin from the quantum confinement effect. The findings elucidate the carrier transport mechanisms within 2D perovskites from their molecular level through Raman spectroscopy, thus providing a promising way for exploring the photo-physical properties in wide-ranged halide perovskites and designing highly efficient perovskite optoelectronic devices.