Barium doping effect on the photovoltaic performance and stability of MA_0.4FA_0.6Ba_xPb_1-xI_yCl_3-y perovskite solar cells

Perovskite solar cells (PSCs) have earned widespread attention owing to its fast-growing power conversion efficiency (PCE). However, there are some challenges for this type of solar cells. The toxicity issue, current density-voltage (J-V) hysteresis, and uncertain stability hinder commercialization. In this study, we developed the PSCs with MA_0.4FA_0.6Ba_xPb_1-xI_yCl_3-y film as active layer. The MA_0.4FA_0.6Ba_xPb_1-xI_yCl_3-y film with various barium doping concentrations were fabricated by solvent engineering method. We investigate the surface morphology, crystal orientation, and optical property of various perovskite films. Furthermore, the in situ grazing-incidence wide-angle X-ray scattering (in-situ GIWAXS) is used to analyze the heating crystallization process of perovskite film. We discover that Ba can improve crystallinity and structural stability. For the optimal 5.0 mol% Ba replacement, the PCE of perovskite device is increased to 17.4%, the J-V hysteresis can be completely eliminated and the device demonstrates long-term stability.