Metal element doping in Cs(Pb1 − DE)Br3 for solar cell materials

The structure, and the electronic properties, caused by alkaline earth metals and transition metals substituting for Pb in CsPbBr3 (CPB) are studied by the first principal calculations. Obtained results show that with increasing the dopants concentration, the substitution of Pb with alkali earth metals in CsPbBr3 induces an increase of the electronic band gap, and the direct band gap turns to be the indirect band gap; On the other hand, the substitution of Pb by transition metal elements in CsPbBr3 induces a decrease of the band gap, and the band gap becomes indirect band gap. Doping for Pb may adjust the bandgap of the CsPbBr3 to be 1.3∼1.5eV for fabricating the high efficiency solar cells. The calculated results also prove that the electronegativity of the metal is related the band gap of the doped CPB, which may be related to the outermost s-orbital electrons in the band. The average energy of the s-orbital electrons of the doped metal is highly consistent with the electronegativity of the metal and the change of the band gap after doping. This may open a new way to design the dopants for CPB.