2D solar cell with record high power conversion efficiency based on low-symmetry IV-V₂ bilayer heterostructure

Abstract

The structural, electronic, and optical properties of two-dimensional (2D) low-symmetry orthorhombic IV-V2 bilayer heterostructures (HSs) were investigated using first-principles calculations. Our data show that all the constructed bilayer HSs (SiAs2/GeAs2, SiAs2/SiP2 and SiP2/GeAs2) are stabilized by van der Waals (vdW) interaction. The IV-V2 bilayer HSs exhibit strong visible light absorption and type-II band alignments, which are beneficial for effective separation of photo-generated electron-hole pairs in solar cells. Notably, the 2D SiAs2/GeAs2 HS-based solar cell exhibits a record-high power conversion efficiency (23.98%) higher than those of previously-reported 2D HSs-based solar cells obtained by high-throughput computational screening, owing to its small conduction band offset (0.2 eV) and suitable bandgap (1.49 eV). Our results provide insights into the structures and electronic and photovoltaic properties of the IV-V2 bilayer HSs and may be useful for related 2D solar cell applications.