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.