Investigation of bandgap grading on performances of perovskite solar cell using SCAPS-1D and impedance spectroscopy

The optimization the bandgap of a solar cell is an important consideration to achieve better high efficiency. The ideal bandgap for a solar cell would be one that matches the energy of photons in the solar spectrum, allowing for the efficient absorption of light and conversion into electricity.In the current study; the performance of the perovskite-based solar cells was investigated numerically in band gap from 1.55 to 1.67 (eV) using the one-dimensional SCAPS simulation software not only for the current-voltage characteristics but also for the complex impedance (Z*). The effects of band gap energy of the perovskite absorber layer were evaluated from the J-V curves have shown a maximum efficiency is achieved at 1.61 (eV).From the analysis of the complex impedance (Z*) data only one maximum was observed in the Nyquist and Bode plots. In this case; further analysis war carried to explorethe complex modulus (M*) spectra. Therefore this analysis revealed the existence of tow clears maxima in the Nyquist and Bode plots. The de-convolution approach allowed us to identify the origin of each relaxation. In addition the electrical parameters such as the relaxation time (τ₁), and the (τ₂) related to the electron recombination and ionic transport were extracted. Moreover, a good correlation was obtained between all parameters from the I-V and complex modulus (M*) data to explain the maximum efficiency achieved at 1.61 (eV).These studies basically the combinationof the complex impedance (Z*) and modulus (M*) provide an appropriate path for the optimization of the solar cell efficiency.