The ability to process amorphous or polycrystalline solar cells at low temperature (<150 °C) opens many possibilities for substrate choice and monolithic multijunction solar cell fabrication. Organometal trihalide perovskite solar cells have evolved rapidly over the last two years, and the CH 3 NH 3 PbX 3 (X = Cl, I or Br) material is processed at low temperature. However the first embodiments of the solar cell were composed of high temperature processed (500 °C) compact and mesoporous layers of TiO 2 . The sintering of the mesoporous TiO 2 has been negated by replacing this with a mesoporous insulating scaffold in the meso-superstructured solar cell (MSSC), yet the high temperature processed compact TiO 2 layer still persists in the most efficient devices. Here we have realised a low temperature route for compact TiO 2 , tailored for perovskite MSSC operation. With our optimized formulation we demonstrate full sun solar power conversion efficiencies of up to 15.9% in an all low temperature processed solar cell.