Efficient and stable planar heterojunction perovskite solar cells fabricated under ambient conditions with high humidity

The quality of perovskite film plays an important role on the performance and stability of perovskite solar cells (PSCs). Herein, dense and uniform perovskite (CH3NH3PbI3) films are fabricated by combining hot-casting technique (HCT) and methylamine (CH3NH2) gas treatment (MGT) under ambient conditions with a relative humidity of about 60%. These high quality CH3NH3PbI3 films are further used to fabricate planar heterojunction (PHJ) PSCs with a structure of ITO/PEDOT:PSS/CH3NH3PbI3/PCBM/Ag, showing a power conversion efficiency (PCE) up to 14.2% with negligible hysteresis. More importantly, these PHJ-PSCs show excellent stability, and over 80% of their original efficiencies could be maintained even stored in air (humidity ∼45%) for 20 days without encapsulation. Meanwhile, the PCE up to 13.6% could be achieved for PHJ-PSCs fully fabricated in air including electron transport layer PCBM. The researches provide an ease-of-fabrication method to fully fabricate highly efficient and stable PHJ-PSCs under ambient conditions with high humidity, which would potentially accelerate the commercialization of PHJ-PSCs.