Abstract:

In recent years, hybrid organic–inorganic perovskite light absorbers have attracted muchattention in the field of solar cells due to their optoelectronic characteristics that enable high powerconversion efficiencies. Perovskite-based solar cells’ efficiency has increased dramatically from3.8% to more than 20% in just a few years, making them a promising low-cost alternative forphotovoltaic applications. The deposition of perovskite into a mesoporous metal oxide is aninfluential factor affecting solar cell performance. Full coverage and pore filling into the porous metaloxide are important issues in the fabrication of highly-efficient mesoporous perovskite solar cells.In this work, we carry out a structural and quantitative investigation of CH3NH3PbI3 pore fillingdeposited via sequential two-step deposition into two different mesoporous metal oxides—TiO2and Al2O3. We avoid using a hole conductor in the perovskite solar cells studied in this work toeliminate undesirable end results. Filling oxide pores with perovskite was characterized by EnergyDispersive X-ray Spectroscopy (EDS) in Transmission Electron Microscopy (TEM) on cross-sectionalfocused ion beam (FIB) lamellae. Complete pore filling of CH3NH3PbI3 perovskite into the metaloxide pores was observed down to X-depth, showing the presence of Pb and I inside the pores.The observations reported in this work are particularly important for mesoporous Al2O3 perovskitesolar cells, as pore filling is essential for the operation of this solar cell structure. This work presentsstructural and quantitative proof of complete pore filling into mesoporous perovskite-based solarcells, substantiating their high power conversion efficiency.