Sub-150 °C processed meso-superstructured perovskite solar cells with enhanced efficiency

The ability to process amorphous or polycrystalline solar cells at low temperature (< 150 degrees 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 CH3NH3PbX3 (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 degrees C) compact and mesoporous layers of TiO2. The sintering of the mesoporous TiO2 has been negated by replacing this with a mesoporous insulating scaffold in the meso-superstructured solar cell (MSSC), yet the high temperature processed compact TiO2 layer still persists in the most efficient devices. Here we have realised a low temperature route for compact TiO2, 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.