Abstract
In recent years, hybrid organic–inorganic perovskite light absorbers have attracted much attention in the field of solar cells due to their optoelectronic characteristics that enable high power conversion efficiencies. Perovskite-based solar cells’ efficiency has increased dramatically from 3.8% to more than 20% in just a few years, making them a promising low-cost alternative for photovoltaic applications. The deposition of perovskite into a mesoporous metal oxide is an influential factor affecting solar cell performance. Full coverage and pore filling into the porous metal oxide 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 filling deposited via sequential two-step deposition into two different mesoporous metal oxides—TiO2 and Al2O3. We avoid using a hole conductor in the perovskite solar cells studied in this work to eliminate undesirable end results. Filling oxide pores with perovskite was characterized by Energy Dispersive X-ray Spectroscopy (EDS) in Transmission Electron Microscopy (TEM) on cross-sectional focused ion beam (FIB) lamellae. Complete pore filling of CH3NH3PbI3 perovskite into the metal oxide 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 perovskite solar cells, as pore filling is essential for the operation of this solar cell structure. This work presents structural and quantitative proof of complete pore filling into mesoporous perovskite-based solar cells, substantiating their high power conversion efficiency.
Highlights
Hybrid organic–inorganic perovskites have recently emerged as a promising light harvester material in solar cells due to their distinctive chemical and physical properties and simple synthesis routes
Al2 O3 —was studied with Transmission Electron Microscopy (TEM) on cross-sectional lamellae prepared by focused ion beam (FIB)
The hole conductor free cell based on Al2 O3 /metal oxide/CH3 NH3 PbI3 (MAPbI3) shows Voc of 0.88 V, Jsc of 13.9 mA/cm2, fill factor (FF) of 17%, with efficiency of 2.1%
Summary
Hybrid organic–inorganic perovskites have recently emerged as a promising light harvester material in solar cells due to their distinctive chemical and physical properties and simple synthesis routes. When perovskite was first introduced into solar cells, it was initially deposited via a solution process deposition technique into the mesoporous metal oxide film using a mixture of PbI2 and CH3 NH3 I in a common polar solvent. This technique resulted in wide variations in the performance of the photovoltaic (PV) solar cell devices due to the uncontrolled precipitation of the perovskite, which produced large morphological variations [18]. This study provides better understanding of the formation and the percolation of perovskite within the porous metal oxide
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