An open-access database and analysis tool for perovskite solar cells based on the FAIR data principles

Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42, 400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences. © 2021, The Author(s)

Moisture Induced Crystallographic Reorientations and Effects on Charge Carrier Extraction in Metal Halide Perovskite Solar Cells

Lead halide perovskites LHPs are promising semiconductors for optoelectronic applications. In LHP solar cells, the focus thus far has been mainly on compositional optimization of the MHP layer, without much understanding of the effects of compositional mixing on structure and texture. This is a serious gap in our knowledge because research has shown that texture underlies the mechanisms of charge carrier and ionic transport. Therefore, it is essential to understand the mechanisms that drive changes in texture in LHPs. This work examines the effect of moisture and composition on the structure and texture of LHPs and their impacts on optoelectronic properties. Exposure to moisture is shown to induce a crystallographic reorientation in the polycrystalline films, which is also dependent on the amount of organic cation material present at the surface. For films with an excess of organic halide, moisture was shown to induce texture in the 001 plane contributing to the enhancement of photocurrents and long term device stability. This work shows the importance of texture for the electronic properties of LHPs with a special emphasis on charge carrier extraction in optoelectronic device

Synergistic Role of Water and Oxygen Leads to Degradation in Formamidinium Based Halide Perovskites

Mixed cation metal halide perovskites have shown remarkable progress in photovoltaic applications with high power conversion efficiencies. However, to achieve large scale deployment of this technology, efficiencies must be complemented by long term durability. The latter is limited by external factors, such as exposure to humidity and air, which lead to the rapid degradation of the perovskite materials and devices. In this work, we study the mechanisms causing Cs and formamidinium FA based halide perovskite phase transformations and stabilization during moisture and air exposure. We use in situ X ray scattering, X ray photoelectron spectroscopy, and first principles calculations to study these chemical interactions and their effects on structure. We unravel a surface reaction pathway involving the dissolution of FAI by water and iodide oxidation by oxygen, driving the Cs FA ratio into thermodynamically unstable regions, leading to undesirable phase transformations. This work demonstrates the interplay of bulk phase transformations with surface chemical reactions, providing a detailed understanding of the degradation mechanism and strategies for designing durable and efficient perovskite material