Highly sensitive flexible NO₂sensor composed of vertically aligned 2D SnS₂operating at room temperature

Gas sensors for Internet of Things applications should meet two requisites - low power consumption and easy mounting universally. To satisfy the conditions, gas sensors need to operate at lower temperature and be flexible. In this study, we demonstrate a flexible gas sensor operating at room temperature using vertically aligned two-dimensional SnS₂nanomaterials. The atomic layer deposition (ALD) technique allows direct growth of SnS₂on a plastic substrate. The morphological structure of SnS₂is engineered by effecting changes in the growth temperature and substrate surface, which leads to the excellent sensing performance with respect to NO₂gas along with superior gas selectivity. The gas response is as high as 309 at 1 ppm of NO₂at room temperature, and a reliably high response is also observed even below 500 ppb of NO₂. The fabricated flexible gas sensor exhibits comparable sensing performance and stability upon bending. Furthermore, the ALD achieves excellent uniformity in both the structural and electrical properties of SnS₂over a 4 in. wafer, which is essential for mass production. Therefore, we believe that this work would contribute to realizing the practical application of highly sensitive flexible gas sensors.