Perovskite Adhesion on Rigid Substrates Coated with Metallic Thin Films

According to the unsubsidized Levelized Cost of Energy Comparison published by Lazard, solar energy has decreased from the most expensive source of electricity in 2009 to the least expensive source of energy generation technology in 2020. Perovskite solar cells are particularly attractive due to economic feasibility and relatively simple manufacturing. Perovskites possess a numerous attractive electrical and optical properties and solid-state phenomena that have applications that range from electrical insulation to semiconducting and superconducting characteristics. This class of materials is used in various applications, such as solar cells, LED lights, display screens, memory devices, lasers, and photodetectors. Due to the wide array of applications, mechanical and electrical performance of these materials is of great interest.<br/>Enhancing adhesion between perovskite crystals and the substrates they are synthesized on is a key factor that increases mechanical integrity and overall stability of the photovoltaic device. Furthermore, increased adhesion can lead to performance enhancements of the devices in certain areas, particularly for the electronic properties. Therefore, it is in the interest of manufacturers and researchers to optimize the adhesion of perovskites on their respective substrates. However, reliable determination of perovskite adhesion can prove difficult as the size scale of the devices becomes increasingly smaller. The motivation of this work is to investigate perovskite adhesion on thermally evaporated metallic thin films on rigid substrates. Measurement of perovskite adhesion on substrates could provide useful methodologies and materials substrate-perovskite selection and pairing as well as device optimization.<br/>For this work, various metals and metal composite stacks were deposited onto silicon wafer substrates. Examples include chromium-nickel, chromium-silver, chromium, aluminum, and silver. Thickness of the deposited thin films was controlled and validated through use of a profilometer. Perovskites were synthesized using a solution-based spin coating method. After depositing the perovskites, the morphology of the crystals was analyzed by scanning electron microscopy. Preliminary results show perovskites with lateral dimensions of 1-4 µm were formed on the substrates. Following the morphological analysis of the perovskite crystals, this research will use a modified nanoindentation method to determine the energy required to dislodge the perovskite crystals from the substrate surfaces to characterize the adhesion energy at the perovskite-substrate interface.