Metallic tin substitution of organic lead perovskite films for efficient solar cells

Perovskite solar cells are promising highly efficient and low-cost photovoltaic devices. Nevertheless, the use of the toxic element Pb is still a big challenge for the mass production of highly efficient perovskite solar cells. In this work, a novel and facile technique is presented to fabricate tin-lead alloyed perovskite films using metal precursors and a substitution method. Herein, the perovskite films are formed as a result of the substitution reaction between the Sn metal precursor and methylammonium triiodideplumbate (CH3NH3PbI3, MAPbI(3)) solution carried out at 70 degrees C. The maximum Sn content in perovskite films reaches up to 15% with a substitution reaction time period of 1 day. Through this substitution technique and the unique growth mechanism, a less-toxic and efficient perovskite solar cell with a power conversion efficiency (PCE) of 12.46% is fabricated. It is found that this substituting strategy can exploit a new direction to further explore different active metals substituting less active organic metallic systems with even lower temperature conditions.