Indexed on: 26 May '17Published on: 26 May '17Published in: Journal of the American Chemical Society
The power conversion efficiency (PCE) of lead halide perov-skite photovoltaics has reached to 22.1% with significantly improved structural stability, thanks to the mixed cation and anion strategy. However, the mixing element strategy has not been widely seen in the design of lead-free perovskites for photovoltaic application. Herein, we report a comprehensive study of a series of lead-free and mixed tin and germanium halide perovskite materials. Most importantly, we predict that RbSn0.5Ge0.5I3 possesses not only a direct bandgap within the optimal range of 0.9 - 1.6 eV, but also desirable optical absorp-tion spectrum that is comparable to those of the state-of-the-art methylammonium lead iodide perovskites, favorable effective masses for high carrier mobility, as well as high resistant to the water penetration than the prototype inorganic-organic lead-containing halide perovskite. If confirmed in the laboratory, this new lead-free inorganic perovskite may offer great promise as an alternative highly efficient solar absorber material for photovoltaic application.