Improving the efficiency and stability of perovskite solar cell through tetrabutylammonium hexafluorophosphate post-treatment assisted top surface defect passivation

Interface defects hinder the further development of power conversion efficiency (PCE) and stability of perovskite solar cell (PSC). Herein, a strategy that by using tetrabutylammonium hexafluorophosphate (TBAH) to passivate the top surface defects of perovskite film is proposed. The testing results demonstrate that TBAH can be evenly distributed on perovskite film, effectively passivate Pb2+ defects on top surface. At the same time, the long alkyl chains in TBAH can prevent the perovskite layer from being damaged by water to a certain extent. Eventually, both the efficiency and stability of PSC are improved. The PCEs of small-size PSCs (0.09 cm2) increase from 20.0% for the reference device to 22.0% for device with TBAH treatment, and the 1 cm2 TBAH treated PSC obtains a PCE of 20.5%. What's more, after 700 h aging test in ambient air condition (65 °C, 45–50% relative humidity), the TBAH treated PSC still retains 80% of the initial PCE.