High efficient and long-time stable planar heterojunction perovskite solar cells with doctor-bladed carbon electrode

Hole-transport-layer-free organic-inorganic halide perovskite solar cells are attracted wide attention due to low cost, good reproducibility and long-time stability. However, this type of perovskite solar cell still requires the high process temperature beyond 400 °C. Here, the planar perovskite solar cells with the structure of glass-FTO/ZnO/perovskite/Carbon are successfully fabricated at low temperature. The pristine CH3NH3PbI3 device exhibits the current density of 19.91 mA cm−2 and a power conversion efficiency of 12.81%. Meaningfully, when ammonium chloride is added to the solution of iodide methylamine, the current density and power conversion efficiency of the resulting device can be improved to 20.21 mA cm−2 and 13.62%, respectively. The high performances of device are mainly attributed to compact and smooth surface of perovskite film due to NH4Cl additive. More importantly, the cells also demonstrate good reproducibility, good illumination stability and good long-time stability. The unencapsulated cells can maintain over 90% of the initial power conversion efficiency at 25–28 °C in an ambient environment with 45–60% humidity over 1200 h. The present study can provide a facile and low cost approach to fabricate highly efficient and highly stable perovskite solar cells for the future application.