Processing techniques of perovskite solar cells : Properties depending on material and manufacturing

Abstract: This project investigates how different types of perovskite solar cells, differentiated by choice of materials and processing techniques, compares to each other regarding performance and characterization. The purpose of the project is to further develop perovskite solar cells and to improve the method of manufacturing for better performance. A total of 160 perovskite solar cells are constructed, divided into eight distinct types. Two different perovskites, MAPbI3 and MAFAPbI3, are used and prepared using two different solvents: isopropanol (IPA) and pentanol (PenOH). Furthermore half of the solar cells contain phenethylammonium iodide (PEAI). When completed, the solar cells' performances are measured and compared. Lastly, the solar cells and the perovskites are compared through characterization measurements. An incident-photon-to-current-efficiency (IPCE) spectroscopy is performed on the solar cells to get a better understanding of the efficiency depending on the wavelength of the incident light. An UV-vis-NIR spectroscopy is performed on the thin film to analyze the absorbance and determine the band gap of the material. The pre-crystallized perovskite powders are compared through characterization measurements, such as X-ray Photoelectron Spectroscopy (XPS) characterization and scanning electron microscopy (SEM) measurements. This results in comparing material compositions and optical properties of the solar cells. The results indicate that MAPbI3 (PenOH) is the highest performing type independent of the presence of PEAI. The measured mean power conversion efficiency (PCE) are 15.47% and 13.84% for MAPbI3 (PenOH) with and without PEAI respectively. The best performing individual solar cell contains MAPbI3 (PenOH) with PEAI and has a PCE of 20.21%. On the contrary, MAFAPbI3 (PenOH) with and without PEAI perform the worst. The best improvement of the PCE after two weeks is +22.13%, given by MAPbI3 (PenOH) with PEAI. Generally, solar cells with MAPbI3 have a larger band gap, 1.61 eV, compared to MAFAPbI3's 1.55 eV, regardless of the presence of PEAI. MAPbI3 (PenOH) can convert a larger portion of incident photons to electrical energy, up to almost 80%. MAFAPbI3 (IPA) converts almost as much, over 70%, while MAPbI3 (IPA) and MAFAPbI3 (PenOH) in some measurements barely has a 50% conversion rate.