Tunable near-infrared light emission from layered TiS₃ nanoribbons

The low-dimensional light source shows promise in photonic integrated circuits. Stable layered van der Waals material that exhibits luminescence in the near-infrared optical communication waveband is an essential component in on-chip light sources. Herein, the tunable near-infrared photoluminescence (PL) of the air-stable layered titanium trisulfide (TiS₃) is reported. Compared with iodine particles as a transport agent, TiS₃ grown by chemical vapor transport using sulfur powder as a transport agent has fewer sulfur vacancies, which increases the luminescence intensity by an order of magnitude. The PL emission wavelength can be regulated in the near-infrared regime by thickness control. In addition, we observed an interesting anisotropic strain response of PL in layered TiS₃ nanoribbon: a blue shift of PL was achieved when the uniaxial tensile strain was applied along the b-axis, while a negligible shift was observed when the strain was applied along the a-axis. Our work reveals the tunable near-infrared luminescent properties of TiS₃ nanoribbons, suggesting their potential applications as near-infrared light sources in photonic integrated circuits.