Diagnosis of electrically active defects in CH₃NH₃PbI₃ perovskite solar cells via admittance spectroscopy measurements

The defect properties of CH₃NH₃PbI₃ solar cells with efficiencies ranging from 7.70% to 12.51% were investigated using admittance spectroscopy measurements. Trap levels of the same kind with activation energies varied in the range of 0.16–0.23 eV above the valence band were found for different samples and identified as an interface-type defect. Moreover, the defect parameters, including the capture cross section of the holes, capture lifetime of the holes, and defect density, were extracted, and their relationships with the cell efficiencies were investigated. The results indicated that, compared with other parameters, defect density is a critical factor for CH₃NH₃PbI₃ solar cell performance.