Efficient absorption of Cu2WX4 (X = S, Se, and Te) for photovoltaic application: a theoretical study

Abstract

The expansion of two-dimensional (2D) materials opens up new opportunities for high-efficiency solar cells, beyond traditional 3D crystal structures. Herein, by using the state-of-the-art first-principles computational approach, we have systematically explored a series of 2D Cu-bearing ternary chalcogenides Cu₂WX₄ (X = S, Se, and Te) as acceptors and donors for solar cells due to their ideal optoelectronic properties, for instance, moderate bandgaps, appropriate band edge positions, and excellent visible light absorption characteristics. In particular, the band edge positions of the materials indicate that Cu₂WS₄/Cu₂WSe₄ and Cu₂WS₄/Cu₂WTe₄ bilayers can form type-II band alignment, suitable for the construction of highly efficient solar cell systems. The predicted power conversion efficiencies (PCEs) of the abovementioned bilayers are 15.2% and 21.3%, respectively. In addition, to further examine the photovoltaic performance, we evaluated the polarization angle-dependent photocurrent of nanodevices based on Cu₂WX₄ monolayers by illuminating ray-polarized light into the scattering region. Overall, our study shows that the Cu₂WX₄ monolayers are candidate materials for high-efficiency 2D solar cells.