Additive Effects of Guanidinium Iodide on CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> Perovskite Solar Cells
Taku Kishimoto, Takeo Oku, Atsushi Suzuki, Naoki Ueoka
Abstract
CH 3 NH 3 PbI 3 (MAPbI 3 ) perovskite solar cells with guanidinium (C(NH 2 ) 3 + , GA + ) are fabricated at 150 °C using 3CH 3 NH 3 I:PbCl 2 starting composition in ambient atmosphere, and characterized. Their photoconversion efficiencies and stabilities are improved by the addition of a small amount of GA + . Lattice volumes are increased by the addition of GA + , which confirms the occurrence of GA + substitution at the CH 3 NH 3 site. Energy gaps are decreased by the addition of GA + , which agrees well with the results of molecular orbital calculation and band calculation. The carrier trap density is reduced by the GA + addition, which suggests that lattice defects are suppressed by the GA + doping. Two‐year stabilities of the devices in ordinary air are also investigated, which indicate the effectiveness of GA addition.