Using automated serendipity to discover how trace water promotes and inhibits lead halide perovskite crystal formation

Abstract

Halide perovskite materials have attracted great interest for applications in low-cost, solution-processed solar cells and other optoelectronics applications. The role of moisture in perovskite device degradation and crystal formation processes remains poorly understood.Here we use a data-driven approach to discover the influence of trace amounts of water on perovskite crystal formation by analyzing a comprehensive dataset of 8,470 inversetemperature crystallization lead iodide perovskite synthesis reactions, performed over 20 months using a robotic system. We identified discrepancies between the empirical crystal formation rate in batches of experiments conducted under different ambient relative humidity conditions for each organoammonium cation. We prioritized these using a statistical model, and then used the robotic system to conduct 1,296 controlled interventional experiments in which small amounts of water were deliberately introduced to the reactions. The addition of trace amounts of water promotes crystal formation for 4-methoxyphenylammonium lead iodide and iso-propylammonium lead iodide and inhibits crystal formation for dimethylammonium lead iodide and acetamidinium lead iodide. We also performed thinfilm syntheses of these four materials and determined the grain size distributions using scanning electron microscopy. The addition of water results in smaller grain sizes for dimethylammonium and larger grain sizes for isopropylammonium, consistent with earlier or delayed nucleation, respectively. The agreement between the inverse temperature crystallization and thin film results indicates that this is a feature of the ammonium-water interaction that persists despite differences in the synthesis method.

Highly Emitting Perovskite Nanocrystals with 2-Year Stability in Water through an Automated Polymer Encapsulation for Bioimaging

“…Improving the stability of perovskite NCs in water could also boost their practical application in, for example, electrocatalysis, light emitting diodes (LEDs), lasing, and inks for printable electronic devices. In parallel, the development of automated procedures that enable the rapid fabrication of perovskites NCs in water is crucial for both screening purposes and for scaling up their production, as demonstrated in other systems, − including the robust preparation of NCs/polymer nanobeads where small reaction volumes are needed. , Compared to bench protocols, such routines are also more cost-effective since less time and less manual lab work are required.…”

Dimensional Control over Metal Halide Perovskite Crystallization Guided by Active Learning

“…64 We also included water as an additive since our previous study demonstrated that water content in perovskite precursor solutions affects the crystallinity of MHP single crystals and thin films. 65 Unlike DMSO or DMF, water and formic acid are both hydrogen bond donors and acceptors. 66 When coexisting in solution, DMSO (or DMF) and water (or formic acid) are likely to form hydrogen bonds.…”

Development and Prospects of Halide Perovskite Single Crystal Films

“…Machine learning [ 113–115 ] and high‐throughput physical modeling of perovskites [ 116 ] can also be combined with traditional and automated experimentation to guide and accelerate the discovery of new routes to synthesizing HPSC thin films, new HPSC materials, and increase understanding of structure‐function relationships in these materials. [ 117–121 ]…”