Humidity-Insensitive, Large-Area Applicable, Hot-Air-Assisted Ambient Fabrication of Two-Dimensional Perovskite Solar Cells.

Two-dimensional (2D) layered perovskites (LPs) have shown great potential to deliver high-performance photovoltaic devices with long-term stability. Despite many progresses have been made in film quality and device performance, the LP films are mainly processed in strict conditions and through non-scalable techniques. Here we introduce the hot-air-assisted ambient fabrication technique to prepare LP films for efficient and stable solar cells. The high-quality LP films with good crystallinity, preferable orientation and desirable morphology are obtained by balancing the crystal nucleation and growth processes. Employing the synchrotron-based in situ grazing-incidence X-ray diffraction technique, we find hot air induces the solidification of solutes and forms an intermediate at the air-liquid interface, which transforms into the 3D-like perovskite, followed by the growth of 2D species towards the substrate. The optimal LP film delivers a device power conversion efficiency of 16.36%, the best value for the LP-based solar cells prepared by the non-spin-coating techniques. The solar cell performance is insensitive to the film processing humidity and the device size is up-scalable, which promises the real-world deployment of the LP-based optoelectronic devices. This article is protected by copyright. All rights reserved.