Highly-efficient heterojunction solar cells based on two-dimensional tellurene and transition metal dichalcogenides†
Two-dimensional (2D) semiconductors, such as graphitic carbon nitride (g-C3N4), molybdenum disulfide (MoS2) and phosphorene, with desirable optoelectronic properties and large photoreactive contact area for light absorption, have been widely used as donors and acceptors in high-quality heterojunction solar cells. In this work, by using first-principles density functional theory calculations, we demonstrate that tellurene is a promising candidate 2D semiconductor for designing highly-efficient solar cells due to its desirable optoelectronic properties (an ideal band gap of 1.47 eV, a high carrier mobility up to 2.87 × 103 cm2 V−1 s−1, strong visible light absorption up to 5.0 × 105 cm−1 and high stability in ambient conditions) superior to existing 2D semiconductors used in solar cells. Furthermore, we find that tellurene and TMDs show desirable type II band alignment for constructing highly-efficient heterojunction solar cells with strong charge separation and enhanced sunlight absorption. In particular, the calculated maximum power conversion efficiency (PCE) of our designed Te/WTe2 and Te/MoTe2 heterojunction solar cells can reach as high as 22.5% and 20.1%, respectively.