Strong Covalency-Induced Recombination Centers in Perovskite Solar Cell Material CH 3 NH 3 PbI 3

Inorganic-organic hybrid perovskites are a new family of solar cell materials, which have recently been used to make solar cells with efficiency approaching 20%. Here, we report the unique defect chemistry of the prototype material, CH3NH3PbI3, based on first-principles calculation. We found that both the Pb cations and I anions in this material exhibit strong covalency as characterized by the formation of Pb dimers and I trimers with strong covalent bonds at some of the intrinsic defects. The Pb dimers and I trimers are only stabilized in a particular charge state with significantly lowered energy, which leads to deep charge-state transition levels within the band gap, in contradiction to a recent proposal…

• DO
  Division of Materials Research

  Award: DMR-1104994
• BE
  Basic Energy Sciences

  Award: DE-SC0002623