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

• A suitable band gap for solar cells for CsPbBr 3 , the stable materials for thin film solar cells, by searching the metal replace for Pb, are investigated by the first principle calculations, and proved by Ti-doping in CsPbBr 3 . • Contributions from the valence electrons of doping metal replace for Pb in CsPbBr3, on the band gap is confirmed, which consists with the tendency of the metals’ electronegativity. The structure, and the electronic properties, caused by alkaline earth metals and transition metals substituting for Pb in CsPbBr 3 (CPB) are studied by the first principal calculations . Results show that with increasing the dopants concentration, the alkali earth metals replace Pb in CsPbBr 3 induces the electronic band gap increase, the direct band gap turn to be the indirect band gap; And the transition metal elements replace Pb in CsPbBr 3 induces the band gap decreases become indirect band gap. Doping for Pb may adjust the bandgap of the CsPbBr 3 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.