Two‐dimensional SnP₂Se₆ with gate‐tunable Seebeck coefficient for telecommunication band photothermoelectric detection

Photothermoelectric (PTE) detectors combine photothermal and thermoelectric conversion, surmounting material band gap restrictions and limitations related to matching light wavelengths, have been widely used in telecommunication band detection. Two‐dimensional (2D) materials with gate‐tunable Seebeck coefficient can induce the generation of photothermal currents under illumination by the asymmetric Seebeck coefficient, making them promising candidate for PTE detectors in the telecommunication band. In this work, we report that a newly explored van der Waals (vdW) layered material, SnP 2 Se 6 , possessing excellent field regulation capabilities and behaviors as an ideal candidate for PTE detector implementation. With the assistance of temperature‐dependent Raman characterization, the suspended atomic thin SnP 2 Se 6 nanosheets reveal thickness‐dependent thermal conductivity of 1.4–5.7 W m −1 K −1 at room temperature. The 2D SnP 2 Se 6 demonstrates high Seebeck coefficient ( S ) and power factor ( PF ), which are estimated to be −506 μV K −1 and 207 μW m −1 K −2 , respectively. By effectively modulating the SnP 2 Se 6 localized carrier concentration, which in turn leads to inhomogeneous Seebeck coefficients, the designed dual‐gate PTE detector with 2D SnP 2 Se 6 channel demonstrates wide spectral photoresponse in telecommunication bands, yielding high responsivity ( R = 1.2 mA W −1 ) and detectivity ( D * = 6 × 10 9 Jones) under 1550 nm light illumination. Our findings provide a new material platform and device configuration for the telecommunication band detection.