Strain-Induced Band-Gap Tuning of 2D-SnSSe Flakes for Application in Flexible Sensors

Flexible strain-sensitive-material-based sensors are desired owing to their widespread applications in intelligent robots, health monitoring, human motion detection, and other fields. High electrical-mechanical coupling behaviors of 2D materials make them one of the most promising candidates for miniaturized, integrated, and high-resolution strain sensors, motivating to explore the influence of strain-induced band-gap changes on electrical properties of more materials and assess their potential application in strain sensors. Herein, a ternary SnSSe alloy nanosheet-based strain sensor is reported showing an enhanced gauge factor (GF) up to 69.7 and a good reproducibility and linearity within strain of 0.9%. Such sensor holds high-sensitive features under low strain, and demonstrates an improved sensitivity with a decrease in the membrane thickness. The high sensitivity is attributed to widening band gap and density of states reduction induced by strain, as verified by theoretical model and first-principles calculations. These findings show that a sensor with adjustable strain sensitivity might be realized by simply changing the elemental constituents of 2D alloying materials.