First-principles investigation of photovoltaic material based on lanthanide metals

Searching for photovoltaic materials with high efficiency conforms to the goal for accessing low carbon and sustainable energy. This work explores the properties of RA3X3 compounds (R = La, Sm, Gd, Tb, Dy, Ho, Er; A = Cd, Zn; X = As, P) through a screening process, focusing on the huge potential of RCd3P3 series for further investigation in photovoltaic applications. Results show that RCd3P3 series with a direct or quasi-direct bandgap have an ultra-low exciton binding energy, which is favorable for separating electron and hole pairs. Moreover, these candidates possess high optical absorption in the visible light regions, and the power conversion efficiency limit of RCd3P3 series can be as high as 24.5 % at the thickness of 4 μm. These results could enrich the database of potential solar cells based on lanthanide materials.