Nonlinear optical response and broadband self-powered polarization-sensitive photoresponse in low-symmetric TeSe2
Breaking intrinsic structural symmetry is a fundamental prerequisite for pronounced nonlinear optical responses. Low-symmetry semiconductors with inherent anisotropy enable self-powered optoelectronic conversion and polarization-sensitive functionalities. This work reports the synthesis of low-dimensional van der Waals chain TeSe2 crystals with intrinsic inversion and C3 symmetry breaking. Angle-resolved polarized Raman spectroscopy and second-harmonic generation measurements confirm crystalline anisotropy and nonlinear optical performance. Electrical transport studies reveal p-type conduction with a room-temperature field-effect mobility of 122 cm2 V-1 s-1. The TeSe2 photodetector achieves self-powered detection and linearly polarized light detection across 405–1064 nm, with a photoresponsivity of 77.3 mA/W at 532 nm. The linear photogalvanic effect response is effectively modulated by gate voltage. Density functional theory calculations attribute p-type doping to Te and Se vacancies, while the nonlinear optical origin is linked to strong Berry curvature. Applications in polarization encoding communication and polarization imaging are demonstrated, indicating potential for low-energy-consuming, highly sensitive, on-chip integrated linear polarized photodetectors.