Quasi-One-Dimensional Ta₂PdSe₆ with Strong Topological Surface States for High-Performance and Polarization-Sensitive Terahertz Detection

Topological surface states (TSS) in certain low-dimensional materials impart gapless band structure, massless quasiparticles, and nonlinear optical behavior, enabling distinct advantages for applications in low-energy photon detection. Herein, we develop a quasi-one-dimensional (quasi-1D) transition metal chalcogenide material, Ta₂PdSe₆, with robust TSS, which exhibits a gapless band structure protected by spin-momentum locking and time-reversal symmetry, alongside exceptional transport properties, including a high carrier mobility exceeding 10⁴ cm²·V^-1·s^-1. The quasi-1D chain-like structure induces pronounced anisotropy and significantly reduces carrier scattering, further enhancing transport efficiency. Benefiting from these unique characteristics, the Ta₂PdSe₆-based terahertz (THz) detectors demonstrate outstanding performance with responsivity exceeding 3.63 A·W^-1, a noise equivalent power of 7.4 pW·Hz^-1/2 at 0.28 THz, ultrafast response speed of 1.15 μs, and an exceptional photocurrent anisotropic ratio of 68.3. These findings highlight the significant potential of strong TSS in emerging materials to achieve high-performance and multifunctional THz detection.