Beyond 22% power conversion efficiency in type-II MoSiAs/MoGeN photovoltaic vdW heterostructure.

Nowadays, substantial progress has been achieved in developing advanced solar cell materials, including high-performance two-dimensional (2D) materials like chalcogenides, perovskites, and oxides, along with their van der Waals (vdW) heterostructures. These efforts target enhanced photovoltaic efficiency, cost reduction, and reduced environmental impact. Despite this, challenges remain in improving light absorption, carrier mobility, and power conversion efficiency (PCE), highlighting the need for materials with enhanced optoelectronic properties. Here, we build a 2D MoSiAs/MoGeN vdW heterostructure with a 3.39 Å layer spacing, featuring an indirect band gap of 1.14 eV and type-II band alignment. Computational assessments demonstrate that photo-generated electrons efficiently transfer from the MoSiAs to the MoGeN layer, while holes move in the opposite direction, reducing electron-hole recombination. The heterostructure exhibits excellent stability and optical absorption, with absorption coefficients up to 10 cm across an extensive spectral range from visible to ultraviolet light. Furthermore, it also showcases an impressive electron mobility of 9065 cm V s and a minimal conduction band offset of 0.05 eV, both of which contribute to an enhanced PCE, reaching up to 22.09%. These results position the MoSiAs/MoGeN heterostructure as a promising candidate for solar cell applications due to its superior optoelectronic properties.