The identification and characterization of defect states in hybrid organic–inorganic perovskite photovoltaics

Thin film photovoltaic cells based on hybrid halide perovskite absorbers have emerged as promising candidates for next generation photovoltaics. Here, we have characterized and identified the defect energy distribution in the CH₃NH₃PbI₃ perovskite using admittance spectroscopy, which reveals a deep defect state ∼0.16 eV above the valence band. According to theoretical calculations, the defect state is possibly attributed to iodine interstitials (I_i), which can become the non-radiative recombination centers in the absorber.