Many-body effects on excited-state properties in blue phosphorene nanoribbons

Using density-functional theory combined with the many-body perturbation approach, we have studied the evolution of quasiparticle electronic structure, electron-hole excitations, and optical properties in blue phosphorene nanoribbons. In these low-dimensional systems, the unique dielectric screening results in a significant self-energy correction, which remains impactful even in nanoribbons of large width. Density-functional theory calculations show that armchair and zigzag blue phosphorene nanoribbons exhibit distinct scaling law with width due to their substantially anisotropic effective masses. The quasiparticle band gap evolves as 1/w with ribbon width w and is insensitive to structural chirality, contrasting with that predicted by density functional theory. In the meantime, the optical properties are dominated by exciton effects. The exciton energy and exciton binding energy evolve as 1/w1.5 and 1/w0.8, respectively. The polarizability, evolving as 1/w0.4, underscores the enhanced electron-electron and electron-hole interaction in these one-dimensional systems. Our findings not only provide deep insight into the many-body effects in the electronic and optical properties of low-dimensional materials, but they also show the tunable band gap over a wide range in blue phosphorene nanoribbons, which could find potential applications in optoelectronics.