Polarization-Sensitive Air-Stable Photodetector Based on Ternary Layered Compound FeIn2Se4
Layered chalcogenide compounds have attracted considerable attention for optoelectronic applications due to their rich structural diversity and unique physical properties, including high carrier mobility, ferromagnetism, ferroelectricity, and outstanding optoelectronic and thermoelectric performance. Their tunable bandgaps and strong light absorption render them highly suitable for next-generation photodetectors. However, the environmental instability of many 2D chalcogenides poses a critical challenge for practical applications. In this work, we report a high-performance, polarization-sensitive photodetector based on an air-stable ternary chalcogenide FeIn2Se4. Angle-resolved polarized Raman spectroscopy reveals that the four characteristic Raman modes exhibit a 60° periodic variation in intensity, highlighting the material's pronounced in-plane anisotropy. Benefiting from its strong absorption over a broad spectral range (510–1028 nm), the FeIn2Se4-based device demonstrates reliable photoresponse under multiple excitation wavelengths (405, 473, 515, and 638 nm), showcasing its wideband detection capabilities. Furthermore, XPS measurements after prolonged air exposure confirm the enhanced chemical stability of FeIn2Se4 compared to binary chalcogenides. These findings demonstrate that 2D ternary FeIn2Se4 is an excellent candidate for advanced anisotropic optoelectronic devices, offering broadband photodetection, robust polarization sensitivity, and excellent environmental resilience.