First-Principles Study of the Hexagonal T-Phase PdSe<sub>2</sub> Monolayer and Its Application in Solar Cells
Mukesh Jakhar, Jaspreet Singh, Ashok Kumar, Ravindra Pandey
Abstract
We show that the puckered pentagonal morphology of the layered PdSe2 can be effectively tuned by the lithiation/delithiation process which will induce its phase transition to an octahedral coordinated MoS2-type hexagonal T-phase. Calculations based on density functional theory predict the hexagonal T-PdSe2 monolayer to be stable with the band gap of about 1 eV, the photoabsorption coefficient of ∼5 × 105 cm–1, the electron mobility of 2.3 × 104 cm2 V–1 S–1, and the electron/hole mobility ratio of ∼758 with an anisotropic character. Subsequently, we show that these extraordinary electronic properties can be used to fabricate the type-II heterostructures with the other transition metal dichalcogenides for photovoltaic cells. In particular, the calculated maximum power conversion efficiency of the engineered heterostructures consisted of T-PdSe2/MoS2, P-PdSe2/MoTe2, and P-PdSe2/MoSe2 can reach as high as ∼17, ∼17, and ∼22%, respectively, suggesting the layered PdSe2 to be a candidate material for the next-generation photovoltaic solar cells.