Improvement of Cs2AgBiBr6 double perovskite solar cell by rubidium doping

Cs2AgBiBr6 having a double perovskite structure is expected to achieve non-lead and stable optoelectronic devices, and has received wide attention recently. A strategy for improving of perovskite films via Rubidium cation (Rb+) is for the first time reported. When Rb+ was incorporated into Cs2AgBiBr6 to form (Cs1-xRbx)(2)AgBiBr6, the absorption at long wavelength was enhanced and the density of defect state was reduced without changing the crystal lattice. Furthermore, the mechanism of Rb+ doping to improve double perovskites and the optimal doping ratio was studied in this report. The average power conversion efficiency of doped devices is nearly 15% higher than that of standard devices from 20 devices of each group. Moreover, in the champion device, the power conversion efficiency achieved 1.52% with a high fill factory of 0.788.