Low compressibility of photoelectric properties of layered molecular non-metal halide AsI3

Examining the evolution of photocurrent response in materials under high pressure is an exceptionally effective strategy for deepening our understanding of the intricate relationship between the material structure and its photoelectric-related properties. Herein, we demonstrated the low compressibility of the photoelectric properties of AsI3. With increasing pressure, the photocurrent response of AsI3 under 520 nm laser and xenon lamp illumination exhibits irregular yet gentle fluctuations within the range of 0.67–1.56 nA and 7.4–21.2 nA, respectively, demonstrating low sensitivity to pressure. In stark contrast, the elongation of As–I bonds culminated in a distinct molecular-ionic crystal isostructural transition around 4 GPa, while the bandgap underwent a pronounced monotonic decrease upon compression. This discrepancy may originate from the low dispersion of the valence band and conduction band in AsI3, causing irregular shifts of the valence band maximum and conduction band minimum within the Brillouin zone under pressure. These findings unveil a fresh perspective for gaining a deep understanding of the electronic structure and photoelectric properties of layered non-metal halides, potentially catalyzing the exploration and advancement of high-performance photoelectric materials.