Additive Effects of Guanidinium Iodide on CH3NH3PbI3 Perovskite Solar Cells

CH3NH3PbI3 (MAPbI(3)) perovskite solar cells with guanidinium (C(NH2)(3)(+), GA(+)) are fabricated at 150 degrees C using 3CH(3)NH(3)I:PbCl2 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 CH3NH3 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.

Automated summary

The addition of a small amount of guanidinium (GA(+)) improves the photoconversion efficiencies and stabilities of CH3NH3PbI3 (MAPbI(3)) perovskite solar cells. The lattice volumes are increased by the presence of GA(+), while energy gaps are decreased. Furthermore, the carrier trap density is reduced by GA(+) doping, suggesting the suppression of lattice defects.