A team of researchers has successfully grown large-area ultraflat chiral blue phosphorene (BlueP) on a Cu(111) surface using molecular beam epitaxy (MBE). The resulting BlueP exhibits an ultraflat honeycomb lattice, unlike the typical buckled structure, and displays highly ordered spatial chirality, likely due to rotational stacking with the substrate and interface strain release. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal that the material is metallic and exhibits distinct quantum oscillations in image-potential states, suggesting different local work functions for adjacent chiral units. The study also demonstrates a reversible transformation between chiral and achiral phases of ultraflat BlueP, indicating a unique growth mechanism for phosphorene structures. The ultraflat BlueP has potential applications in polarization optics, spintronics, and chiral catalysis. The research highlights the importance of strain and lattice mismatch in the formation of chiral superstructures and provides insights into the electronic properties of BlueP. The findings contribute to the understanding of two-dimensional materials and their potential for advanced technological applications.A team of researchers has successfully grown large-area ultraflat chiral blue phosphorene (BlueP) on a Cu(111) surface using molecular beam epitaxy (MBE). The resulting BlueP exhibits an ultraflat honeycomb lattice, unlike the typical buckled structure, and displays highly ordered spatial chirality, likely due to rotational stacking with the substrate and interface strain release. Scanning tunneling microscopy (STM) and spectroscopy (STS) reveal that the material is metallic and exhibits distinct quantum oscillations in image-potential states, suggesting different local work functions for adjacent chiral units. The study also demonstrates a reversible transformation between chiral and achiral phases of ultraflat BlueP, indicating a unique growth mechanism for phosphorene structures. The ultraflat BlueP has potential applications in polarization optics, spintronics, and chiral catalysis. The research highlights the importance of strain and lattice mismatch in the formation of chiral superstructures and provides insights into the electronic properties of BlueP. The findings contribute to the understanding of two-dimensional materials and their potential for advanced technological applications.