Two-dimensional -PC3: A novel direct band gap semiconductor with ultrahigh carrier mobility for photovoltaics

Here, we report a novel two-dimensional phosphorus carbide, named gamma-PC3, and determine its structural, electronic, transport, and photovoltaic characteristics utilizing density functional theory. gamma-PC3 consists of P atom linked benzenes and has an anisotropic orthorhombic crystal structure. It exhibits excellent stability, as confirmed by the cohesive energy (6.38 eV/atom), phonon dispersion (the ultimate strain is as high as 13 %), molecular dynamics simulation, elastic modulus, and strain-stress relationship. The gamma-PC3 monolayer has direct band gap (1.13 eV), ultrahigh electron mobility (up to 7.25 x 104 cm2 V-1 s-1 along armchair direction), and high optical absorption coefficient (up to 105 cm -1). By changing the stacking sequence and thickness to multilayer geometries or applying the tensile uniaxial strain to the monolayer geometry, its direct band gap and optical absorption coefficient can be effectively tuned. The gamma-PC3/MoS2 heterojunction has a photoelectric conversion efficiency of 15.54 %, which demonstrates that gamma-PC3 is a promising semiconductor for photovoltaics.