Low-Symmetry 2D Perovskite CaNb2O6 for Polarization-Sensitive UV Photodetection

Polarization-sensitive photodetection in ultraviolet (UV) range has demonstrated broad applications in both military and civilian fields. As the key component of polarized UV photodetectors, semiconducting materials with wide bandgaps and intrinsic low-symmetry are highly desired. Herein, perovskite calcium niobate (CaNb2O6) is re-introduced to the family of two-dimensional (2D) layered materials for UV-polarized photodetection. Using a simple vapor phase epitaxy growth process, CaNb2O6 nanosheets are successfully synthesized, which can be scaled down to monolayers with thickness of about 0.8 nm. The anisotropic structural, vibrational, and optical properties of CaNb2O6 are systematically investigated. Photodetectors based on 2D CaNb2O6 present a large dichroic ratio of 2.1 at 375 nm light irradiation, exceeding most of reported UV photodetectors, and the large anisotropic ratio also contributes to a high-resolution polarization imaging. This work demonstrates that the 2D CaNb2O6 has promising potential for developing next-generation polarized UV detecting and imaging technology.