Structural and optoelectronic properties of the inorganic perovskites AGeX3 (A = Cs, Rb; X = I, Br, Cl) for solar cell application

We predict the structural, electronic and optic properties of the inorganic Ge-based halide perovskites AGeX3 (A = Cs, Rb; X = I, Br, Cl) by using first-principles method. In particular, absolute electronic energy band levels are calculated using two different surface terminations of each compound, reproducing the experimental band alignment.