Monolayer HfTeSe4: A Promising Two-Dimensional Photovoltaic Material for Solar Cells with High Efficiency.

Currently, atomically thin materials with high photovoltaic performance are urgently needed for applications in solar cells. Herein, by using first-principles calculations, we propose an excellent two-dimensional photovoltaic material, monolayer HfTeSe4, which can be exfoliated feasibly from its layered bulk. It behaves in the semiconductor character with a moderate direct gap of 1.48 eV and exhibits remarkable absorbance coefficient of ∼105 cm-1 in the visible-light region. Meanwhile, monolayer HfTeSe4 shows ultrahigh photocurrent and a long carrier recombination lifetime. Also, strain engineering can further modulate the recombination time of carriers. Moreover, the heterostructure between HfTeSe4 and Bi2WO6 is proposed as potential solar cells with the solar conversion efficiency up to ∼20.8%. These extraordinary properties combined with its experimental feasibility makes monolayer HfTeSe4 particularly promising for photovoltaic device applications.