Solution-processed perovskite solar cells using environmentally friendly solvent system

Hybrid inorganic-organic perovskite solar cells have attracted great attention with power conversion efficiencies exceeding 20% using dimethylformamide or dimethyl sulfoxide for the deposition of the perovskite films. Replacing the toxic solvents with non-toxic solvents is one of the key challenges to realize industrial scale commercialization for the perovskite photovoltaics. Here, environmentally friendly solvent systems are employed for processing the perovskite active layer by a two-step spin-coating approach: aqueous Pb(NO3)2 is first spin-coated on mesoporous TiO2 film, and followed by spin-coating of methylammonium iodide in isopropanol. We found that the resulting perovskite was homogeneously covered on the TiO2 surface with relatively high coverage. The best performing perovskite solar cell shows a power conversion efficiency of 13.7% under standard conditions (AM1.5, 100 mW cm− 2).