Efficient lead acetate sourced planar heterojunction perovskite solar cells with enhanced substrate coverage via one-step spin-coating

摘要

In planar heterojunction (PHJ) perovskite solar cells (PerSCs) without mesoporous metal oxide skeleton, there is challenge of formation perovskite film with full coverage to the conductive substrate through solution-process the lead halide precursors. Selecting a lead source with more volatile byproducts is an effective approach to obtain much smoother films with smaller and fewer pinholes. Herein, we demonstrate efficient CH_3NH_3PbI_3/PCBM PHJ PerSG by using lead acetate (Pb(Ac)_2) as lead precursor. The morphology of the perovskite thin films were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), respectively, and the crystalline quality of the perovskite films were investigated by X-ray diffraction (XRD) spectroscopy. Time-resolved photoluminescence (TRPL) was used to investigate the PL lifetime of the perovskite film. The perovskite film derived from Pb(Ac)_2 shows enhanced surface coverage and improved photoluminescence lifetime in comparison with PbI_2 sourced perovskite film. Averaged over 20 individual devices, the power conversion efficiency (PCE) of devices derived from Pb(Ac)_2 reaches 14.81%, much higher than PbI_2 sourced devices by one-step (8.23%) or two-step (10.58%) spin-coating.