In this work, the solution-processed CH 3 NH 3 PbI 3 perovskite/copper indium disulfide (CuInS 2 ) planar heterojunction solar cells with Al 2 O 3 as a scaffold were fabricated at a temperature as low as 250°C for the first time, in which the indium tin oxide (ITO)-coated glass instead of the fluorine-doped tin oxide (FTO)-coated glass was used as the light-incidence electrode and the solution-processed CuInS 2 layer was prepared to replace the commonly used TiO 2 layer in previously reported perovskite-based solar cells. The influence of the thickness of the as-prepared CuInS 2 film on the performance of the ITO/CuInS 2 ( n )/Al 2 O 3 /(CH 3 NH 3 )PbI 3 /Ag cells was investigated. The ITO/CuInS 2 (2)/Al 2 O 3 /(CH 3 NH 3 )PbI 3 /Ag cell showed the best performance and achieved power conversion efficiency up to 5.30%.