Area-Scalable ZnSnO Electron Transport Layer for Highly Efficient and Stable Perovskite Solar Modules.

The development of a scalable chemical bath deposition (CBD) process facilitates the realization of electron-transporting layers (ETLs) for large-area perovskite solar modules (PSMs). Herein, a method to prepare a uniform and scalable thick ZnSnO ETL by CBD, which yielded high-performance PSMs, is reported. This ZnSnO ETL exhibits excellent electrical properties and enhanced optical transmittance in the visible region. Moreover, the ZnSnO ETL influences the perovskite layer formation, yielding enhanced crystallinity, increased grain size, and a smoother surface, thus facilitating electron extraction and collection from the perovskite to the ETL. ZnSnO thereby yields PSMs with a remarkable photovoltaic performance, low hysteresis index, and high device reproducibility. The champion PSM exhibited a power conversion efficiency (PCE) of 22.59%, being among the highest values published so far. In addition, the CBD ZnSnO-based PSMs exhibit high stability, retaining more than 88% of initial efficiency over 1000 h under continuous illumination. This demonstrates that CBD ZnSnO is an appropriate ETL for high-efficiency PSMs and a viable new process for their industrialization.