Dual Photoresponse and Room-Temperature Ferromagnetism in Iron-Doped Tin Selenide Nanosheets Photoelectrochemical Photodetectors

Multifunctional SnSe-based platforms are vital for next-generation integrated optoelectronics. Herein, we demonstrate Fe-doped SnSe nanosheets concurrently exhibiting enhanced photoresponse and room-temperature ferromagnetism. The Fe2+ dopants introduce sub-band trapping states and facilitate lattice contraction, which synergistically suppress charge recombination and promote charge separation. Systematic PEC measurements reveal that the Fe-doped SnSe photodetector (Sn0.95Fe0.05Se) exhibits a significantly enhanced photoresponse compared to pristine SnSe. In 0.5 M KOH, Sn0.95Fe0.05Se-based photodetector reaches 115.29 μA W–1 responsivity and 4.39 × 1010 Jones detectivity (420 nm, 0.6 V), roughly 4.8- and 3.8-fold higher than pristine SnSe, respectively. Furthermore, under 420 nm illumination, the device demonstrates a fast photoresponse (τres/τrec = 0.22/0.11 s) and robust 6000 s stability under white light at 0.6 V. This work elucidates the role of Fe2+ ions in modulating carrier dynamics and inducing high-temperature ferromagnetism (Tc ≈ 885 K), offering insights into SnSe-based bifunctional optoelectronic and spintronic devices.