Ultrabroadband Photoconductive Topological Material with Exceptional Multienvironmental Stability

A topological crystalline insulator (TCI) constitutes a valid candidate for optoelectronic applications owing to its broad spectral absorption, ultrafast response, and excellent stability. Thus far, the upscaling of the synthetic approach for TCIs has not been accomplished. Here, we proposed the one-step upscaling of a 6 in. two-dimensional (2D) SnSe_0.9Te_0.1 TCI for highly robust broadband photodetection from visible to LWIR. The photoresponsivity and detectivity of the SnSe_0.9Te_0.1-based photodetector corresponded to 3.34 A W^-1 and 3.1 × 10¹¹ Jones for 532 nm, 11.17 A W^-1 and 1.07 × 10¹² Jones for 1064 nm, 0.01 A W^-1 and 1.03 × 10¹⁰ Jones for 1550 nm, and 0.002 A W^-1 and 5.36 × 10⁸ Jones for 4000 nm, respectively. In addition, the evident photoresponse was perceived by the subtle thermal radiation of human fingers. We systematically evaluated the performance reliability and multienvironmental stability of the SnSe_0.9Te_0.1-based photodetector under various conditions, including prolonged air exposure, thermal stress, humidity, and water immersion. We proposed a topological electronic structure of SnSe_0.9Te_0.1 by the atomic substitution of Te into orthorhombic SnSe, permitting the rock-salt phase transition in a localized area, resulting in highly robust broadband photodetection.