Enhance the efficiency of perovskite solar cells using W doped SnO2 electron transporting layer

For low temperature (<= 180 degrees C) processed perovskite solar cells (PSCs), SnO2 has been proven to be one of the most effective electron transporting layer. However, problems, such as poor electric conductivity and high defect density, inevitably exist in the SnO2 films which are fabricated using low temperature solution methods. Element doping of SnO2 film is a feasible strategy to alleviate the above problems. Herein, W doping of the SnO2 is realized through addition of ammonium tungstate hydrate into the molecular precursor of SnO2. The W doped SnO2 film exhibits higher conductivity, and can better extract and transport the electrons from the perovskite films. Hence, power conversion efficiency is boosted from 20.60 % for the reference PSCs to 21.83 % for PSCs fabricated on 2.5 mg mL(-1) ammonium tungstate hydrate doped SnO2 films.