Defect-engineered monolayer TlBiSe 3 for self-powered polarization detection and reconfigurable spin encoding

Abstract Defect engineering enables precise manipulation of optoelectronic and spintronic properties in two-dimensional (2D) semiconductors. Density functional theory (DFT) calculations reveal that atomic vacancies in monolayer TlBiSe 3 induce semiconductor-to-metal transition or semiconductor-to-semimetal transition through band structure reconstruction. In the infrared-visible spectrum (0.1–3.0 eV), defect-engineered monolayer TlBiSe 3 exhibits up to 5.3-fold enhanced self-powered photocurrents via the linear photogalvanic effect (PGE) compared to pristine counterparts. This enhancement enables polarization-sensitive detection, with photocurrent exhibits characteristic cos ( 2 θ ) dependence on polarization angle. Notably, the Se 3 -vacancy configuration achieves a peak photocurrent density of 3.17 at 1.9 eV, while the Se 1 -vacancy yields a record extinction ratio (ER) of 510.08 at 2.6 eV. Furthermore, Bi vacancy generates near-unity spin-polarized currents ( > 9 0 % efficiency) and two-bit reconfigure spin transport channels through photon energy (0.1/0.8 eV) or polarization angle ( 0 ° / 90 ° ) modulation. These findings establish defect-engineered TlBiSe 3 as a versatile platform for self-powered polarization detectors and reconfigurable spin encoders.