Scalable Preparation of High‐Performance ZnO–SnO2 Cascaded Electron Transport Layer for Efficient Perovskite Solar Modules

Perovskite solar cells are the fastest‐growing photovoltaic technology in recent years. However, together with the stability, the low‐cost and high‐quality preparation of large‐area modules still limits their commercialization process. Herein, a scalable and high‐performance ZnOSnO2 cascade double‐layer electron transport layer (ETL) for efficient and stable perovskite modules is reported. The cascaded ETL is fabricated using a simple spray pyrolysis coating combined with the blade coating process, which not only effectively improves the interface stability by avoiding the protonation of ZnO to maintain its high electron mobility, but also provides a much smoother surface for the crystallization of perovskites. In addition, the well‐matched conduction band level between SnO2 and perovskites ensures the improvement of open‐circuit voltage. Subsequently, combined with the blade‐coated perovskite layer and hole transport layer film, large‐area planar perovskite modules are successfully prepared. These high‐quality films enable the perovskite solar modules to achieve impressive efficiencies of 17.8% in the module size 6 × 6 cm2 and 16.6% in a size of 10 × 10 cm2. The obtained module also shows excellent reproducibility and stability. The high‐performance ETL and the related deposition method developed in this work are promising for applications in the industrial scalable perovskite modules’ fabrication. The low‐cost, scalable, and high‐performing ZnOSnO2 cascaded electron transport layer based on spray coating and blade coating is developed and demonstrates the superior advantages in electrons’ extraction, energy band matching, interface stability, and crystallization tailoring for perovskite films. Further combined with the same scalable blade‐coated perovskite film and hole transport layer, efficient planar modules with high reproducibility are facilely realized.