The authors investigate the stability, transport, and electro-optical properties of a novel Ga₂TeS monolayer with a diamondene-like structure using density-functional theory (DFT) + G₀W₀ + BSE calculations. They find that the Ga₂TeS monolayer exhibits dynamical and thermal stabilities, high electron mobility (over 2000 cm²·V⁻¹·s⁻¹), a moderate direct bandgap, and superior light absorption in a broad region. The optical spectrum is dominated by excitons, with a favorable exciton binding energy. Under biaxial strain, the bandgap becomes tunable, electron mobility improves, and visible-light absorption significantly enhances. These findings suggest that the Ga₂TeS monolayer has potential as an optoelectronic material. The study also explores the strain effects on the material's properties, providing insights into its potential applications in electronics and optoelectronics.The authors investigate the stability, transport, and electro-optical properties of a novel Ga₂TeS monolayer with a diamondene-like structure using density-functional theory (DFT) + G₀W₀ + BSE calculations. They find that the Ga₂TeS monolayer exhibits dynamical and thermal stabilities, high electron mobility (over 2000 cm²·V⁻¹·s⁻¹), a moderate direct bandgap, and superior light absorption in a broad region. The optical spectrum is dominated by excitons, with a favorable exciton binding energy. Under biaxial strain, the bandgap becomes tunable, electron mobility improves, and visible-light absorption significantly enhances. These findings suggest that the Ga₂TeS monolayer has potential as an optoelectronic material. The study also explores the strain effects on the material's properties, providing insights into its potential applications in electronics and optoelectronics.