Strain-tunable 2D phosphorene oxide monolayers: achieving direct bandgap and ultrahigh carrier mobility for advanced photovoltaic materials

Abstract The exploration of novel two-dimensional (2D) solar cell materials to address the demands of next-generation electronic applications remains a critical priority. By employing density functional theory (DFT) and global structure prediction methods, we propose two new 2D configurations: 2D phosphorus (2D P) and 2D phosphorus oxide (2D PO). The latter is synthesized through surface oxygen functionalization of 2D P. Phonon dispersion analyses and first-principles molecular dynamics (MD) simulations confirm that both structures demonstrate exceptional dynamical and thermal stability. Notably, 2D P exhibits an indirect bandgap semiconductor behavior, whereas 2D PO possesses a direct bandgap. Under strain modulation, the direct bandgap characteristic of 2D PO remains stable across its entire strain-tolerant range (0–2.3 eV), with the bandgap tunable to the ideal value of 1.5 eV for solar energy applications. Carrier mobility calculations reveal that 2D PO achieves a remarkably high mobility of approximately 0.64 × 10 4 cm 2 V −1 s −1 , surpassing that of MoS 2 and black phosphorene by orders of magnitude. Furthermore, optical property analyses indicate strong light absorption within the visible spectrum for 2D PO. These unique electronic properties, combined with superior optical performance and structural robustness, position 2D PO as a highly promising candidate for advanced solar cell technologies and nanoelectronic devices.