Exploring charge carrier processes in perovskite solar cells using small perturbation methods
The global search for technologies capable of generating energy in a clean, renewable, and sustainable way has been increasing and shifted the focus of research to materials and devices capable of meeting these needs. Perovskite solar cells have attracted much attention due to their high light-to-electricity conversion efficiency (25.7%) and low cost. However, electronic and electrochemical processes such as recombination, movement, and accumulation of charges and ions at cell interfaces directly affect their efficiency and long-term stability. A crucial tool to understand these processes is Electrochemical Impedance Spectroscopy (EIS). This work inserts this context by preparing perovskite solar cells with reproducible photovoltaic results. The morphology of ETL and perovskite layers was evaluated by Scanning Electron Microscopy (SEM), showing the uniformity of layers. The compiled photovoltaic parameters determined over time showed a trend of increasing efficiency and reproducibility of the results. It was possible to obtain a solar cell with the highest efficiency value recorded in the laboratory, corresponding to 15.5% and 18.6% in forward and reverse measurements, respectively. The EIS experiments in the dark, varying the alternating current potential, resulted in a pseudo-linear region between 5 and 20 mV and allowed the investigation of ion diffusion processes in the solar cell.