Developing an effective scalable fabrication process for perovskite solar cells is urgent to getting perovskite photovoltaic technology market‐ready. Perhaps due to the relatively cost‐effective setup and tunable fabrication processes, the vast majority of research efforts have been dedicated to the development of solution‐based scalable processes. Comparatively, the vacuum thermal evaporation processes have not been studied in‐depth, regardless of their advantages in reproducibility, scalability, extendable applications, safety, and toxicity. Here possible opportunities and challenges are discussed in utilizing the vacuum thermal evaporation technique for mass production of large‐area perovskite solar modules. While this process has technical and economical potential, more research should be warranted.

Organic–inorganic or inorganic metal halide materials have emerged as a promising candidate for a resistive switching material owing to their ability to achieve low operating voltage, high on–off ratio, and multi‐level switching. However, the high switching variation, limited endurance, and poor reproducibility of the device hinder practical use of the memristors. In this study, a universal approach to address the issues using a van der Waals metal contact (vdWC) is reported. By transferring the pre‐deposited metal contact onto the active layers, an intact junction between the metal halide and contact layer is formed without unintended damage to the active layer caused by a conventional physical deposition process of the metal contacts. Compared with the thermally evaporated metal contact (EVC), the vdWC does not degrade the optoelectronic quality of the underlying layer to enable memristors with reduced switching variation, significantly enhanced endurance, and reproducibility relative to those based on the EVC. By adopting various metal halide active layers, versatile utility of the vdWC is demonstrated. Thus, this vdWC approach can be a useful platform technology for the development of high‐performance and reliable memristors for future computing.

Chemical bath deposition is widely used to deposit SnOx as an electron transport layer in perovskite solar cells (PSCs). The conventional recipe uses thioglycolic acid (TGA) to facilitate attachments of SnOx particles onto the substrate. However, nonvolatile TGA has been reported to harm the operational stability of PSCs. In this work, we introduced a volatile oxalic acid (OA) as an alternative to TGA. OA, a dicarboxylic acid, functions as a chemical linker for the nucleation and attachment of particles to the substrate in the chemical bath. Moreover, OA can be readily removed through thermal annealing followed by a mild H2O2 treatment, as shown by FTIR measurements. Synergistically, the mild H2O2 treatment selectively oxidizes the surface of the SnOx layer, minimizing nonradiative interface carrier recombination. EELS (electron‐energy‐loss‐spectroscopy) confirms that the SnOx surface is dominated by Sn4+, while the bulk is a mixture of Sn2+ and Sn4+. This rational design of a CBD SnOx layer leads to devices with T85∼1,500 h, a significant improvement over the TGA‐based device with T80∼250 h. Our champion device reached a power conversion efficiency of 24.6%. This work offers a rationale for optimizing the complex parameter space of CBD SnOx to achieve efficient and stable PSCs.This article is protected by copyright. All rights reserved