Is the Bandgap of Bulk PdSe ₂ Located Truly in the Far‐Infrared Region? Determination by Fourier‐Transform Photocurrent Spectroscopy

2D bulk PdSe2, a group 10 noble metal dichalcogenide, is recognized as newly found far-infrared material with bandgap energy (E G) of ≈0.05 eV and thus has attracted much attention an optoelectronic material. However, the PdSe2 subject controversial debate middle ≈0.3 also reported by electrical transport measurements. Although determining E G optical absorption measurement essential, difficulty lies in weak caused indirect transition. Herein, it quantitatively estimated that indeed 0.5 at 40 K based on highly sensitive spectroscopic method Fourier-transformation photocurrent spectroscopy. suggested potential application should be properly selected.