Trap states in multication mesoscopic perovskite solar cells: A deep levels transient spectroscopy investigation

This work presents a study of trap levels in a mesoscopic multication lead halide perovskite solar cell structure. The investigation is performed by combining capacitance measurements, admittance measurements, Deep Level Transient Spectroscopy (DLTS), and Optical DLTS. We found a donor level with an energy of 0.2 eV below the conduction band of perovskite. The donor density reaches a concentration of 1018 cm−3 in the accumulation region present at the interface between the perovskite and transporting layers. Other two deep trap levels are found with energies of 0.57 eV and 0.74 eV. The first level is related to a hole trap while the second one to an electron trap.