Slot-Die-Coated Zinc Tin Oxide Film For Carbon-Based Methylammonium-Free Perovskite Solar Cells

At the laboratory scale, the spin coating technique is commonly used for depositing an electron transporting layer (ETL) in perovskite solar cells (PSCs). However, this technique is unsuitable for scaling up production. To enable large-scale deposition, slot-die coating, — a promising scalable technique and low operational cost processing, — has been proposed for depositing thin and uniform films across large areas. In this work, scalable slot-die coating processes of amorphous zinc tin oxide (ZTO) as ETLs are illustrated for carbon-based methylammonium-free PSCs. The amorphous ZTO was selected because of its excellent optical and electronic properties such as high electrical conductivity, high electron mobility, and high transparency. Slot-die-coated ZTO thin films were prepared from a proprietary homemade slot-die setup on a 3-axis computer numerical control (CNC) platform. Various thicknesses of ZTO thin films were utilized by changing the speed of the slot-die head. The device using slot-die-coated ZTO films with a film thickness of 48nm was found to exhibit the best device maximum power conversion efficiency of 9.92%, which is comparable to that of the device using spin-coated ZTO film. This work demonstrates the potential of the slot-die coating technique to replace the conventional spin-coating method in the fabrication of high efficiency and scalable PSCs.