Fabrication and characterization of CH 3 NH 3 PbI 3 solar cells with added guanidinium and inserted with decaphenylpentasilane

In this work we investigated the effects of the addition of guanidinium [C(NH 2 ) 3 ; GA] on CH 3 NH 3 PbI 3 perovskite solar cells fabricated at a high temperature of 190°C in atmospheric air. The addition of GA iodide and the insertion of decaphenylpentasilane between the perovskite and hole transport layer improved the external quantum efficiency and short-circuit current density, and the conversion efficiencies were stable after 1 month. X-ray diffraction showed that the lattice constant of the perovskite crystals was increased by the addition of GA, and addition of GA also improved the surface morphology. First-principles calculations on the density of states and band structures showed reduction of the total energy by the addition of GA and the effectiveness of the nitrogen atoms in GA.