Infiltration of CsPbI3:EuI2 Perovskites into TiO2 Spongy Layers Deposited by gig-lox Sputtering Processes
C. Spampinato, Paola La Magna, Salvatore Valastro, Emanuele Smecca, Valentina Arena, Corrado Bongiorno, Giovanni Mannino, Enza Fazio, Carmelo Corsaro, F. Neri, Alessandra Alberti
Abstract
Perovskite solar cells have become a popular alternative to traditional silicon solar cells due to their potential to provide high-efficiency, low-cost, and lightweight solar energy harvesting solutions. However, the multilayer architecture of perovskite solar cells demands careful investigation of the interaction and interfacing between the various layers, as they play a crucial role in determining the overall performance of the cell. In this context, the present work aims at analyzing the coupling between a spongy transparent electron-transporting layer (ETL) and perovskite in a formulation CsPbI3:EuI2. The ETL used in this work is a transparent mesoporous TiO2 layer called “gig-lox” (grazing incidence angle geometry–local oxidation), which has been optimized to boost the interfacing with the perovskite for achieving a highly interconnected blend of materials. The gig-lox TiO2 ETL shows a high surface wettability with respect to the perovskite solution, especially after pre-annealing at 500 °C, and this enables the perovskite material to deeply infiltrate throughout it. The surface wettability of the gig-lox TiO2 has been estimated by contact angle measurements, while the deep infiltration of the perovskite material has been demonstrated through X-ray diffraction and transmission electron microscopy analyses. Thanks to the achieved deep infiltration, the photo-generated charge injection from the perovskite into the mesoporous oxide is enhanced with respect to the use of a planar compact oxide, as shown by the photoluminescence measurements. The mainstay of the approach resides in the ETL that is deposited by a solvent-free sputtering method and is up-scalable for high industrial throughput.