Large scale flexible perovskite solar cells fabricated by slot die coating

Perovskites are particularly promising for flexible solar cell applications, because of low-cost and facile integration to flexible substrates. Flexible substrates, however, require lower processing temperatures. Reducing the processing temperature to accommodate inexpensive flexible substrates was a central challenge in this work. Air stability and moisture resistance were improved through molecular engineering of the perovskite materials using an advanced formula containing multiple cations, and through device structure optimization. A spin-coating based solution process was optimized to grow highly crystalline perovskite films within a few seconds in air. Integrated perovskite solar cell module shows enhanced air stable and moisture resistance, with an average efficiency reaching 17% on flexible substrates. We also demonstrate the feasibility of scale-up using slot die coating, up to 100 mm x 75 mm in size.