Wide Band Gap P3S Monolayer with Anisotropic and Ultrahigh Carrier Mobility.

Phosphorene has offered an additional advantage for developing new optoelectronic devices due to its anisotropic and high carrier mobility. However, its instability in air causes a rapid degradation of the performance of the device. Thus, improving the stability of phosphorene while maintaining its original properties has become the key to the development of high-performance electronic devices. Herein, we propose that the formation of two-dimensional (2D) P-rich P-S compounds could achieve this goal. First-principles swarm-structural searches revealed two previously unkonwn P3S and P2S monolayers. The P3S monolayer, consisting of n-bicyclo-P6 units along the armchair direction, exhibits anisotropic and wide band gap characteristics. Interestingly, its carrier mobility reaches 1.11 × 104 cm2 V-1 s-1 and is much higher than in phosphorene. Its electronic band gap and optical absorption coefficients in the ultraviolet region reach 2.71 eV and 105 cm-1, respectively. Additionally, the P3S monolayer has a high structural stability and resistance to air oxidation.