Investigation of charge recombination processes in perovskite solar cells
The growing global search for technologies capable of generating energy in a clean and renewable way in a sustainable way started to direct the focus of research to materials and devices capable of meeting these needs. Perovskite solar cells have attracted attention for the study of the material due to their promising light conversion efficiency, currently reaching 25.7%. However, electronic and electrochemical processes such as recombination, movement and accumulation of charges and ions at cell interfaces directly affect their efficiency and stability. Electrochemical Impedance Spectroscopy (EIE) is an important tool for understanding these processes. In order to evaluate these mechanisms in a systematic way, it is essential to obtain reproducible results regarding the photovoltaic parameters of solar cells. This work is part of this context by carrying out experiments on the assembly of solar cells seeking reproducible results. The morphology of the ETL and perovskite layers were evaluated by Scanning Electron Microscopy (SEM), obtaining uniform films. The photovoltaic parameters were compiled observing a tendency to increase the reproducibility of the results. It was possible to obtain a solar cell with a record efficiency value, corresponding to 15.5% and 18.6% in forward and reverse measurements, respectively. The EIE was performed in the dark by varying the alternating current potential, looking for a region of pseudo-linearity. A pseudo-linear region between 5 and 20 mV was observed, in addition to identifying ion diffusion processes in the solar cell. Finally, this work also brings proposals for modifications and investigations in solar cells that will be carried out in the future.