Fabrication of all printed inverted perovskite solar cells with transfer printed electron transporting layers

We demonstrated the low-cost, eco-friendly fabrication techniques for inverted perovskite solar cells (iPSCs) with multilayered electron transporting layers using fullerene derivative (PCBM) and ZnO nanoparticles (NPs) by combining the meniscus-coating, push-coating, and transfer-printing techniques. We fabricated the multilayered planar iPSCs by low-temperature printing process not higher than 120(degrees)C. Using meniscus coating method by reciprocating the glass rod back and forth repeatedly for 2-10 times, the material usage of PCBM and toxic chlorobenzene for iPSCs to 1/15 similar to 1/20 compared with the conventional spin-coating method, and 1/10 for ZnO NPs without extending the tact time. The material utilization rate became about 50% and 100% for meniscus- and push-coating, and a pin-hole-free uniform film was obtained for meniscus coating. We also reduced the initial degradation of perovskite layer during the deposition of ZnO onto the perovskite layer and improved the photovoltaic properties by the transfer-printing of ZnO from "wet-PDMS" stamp onto the thin PCBM film coated perovskite layers.