Inorganic–organic hybrid materials represent a large share of newly reported structures, owing to their simple synthetic routes and customizable properties¹. This proliferation has led to a characterization bottleneck: many hybrid materials are obligate microcrystals with low symmetry and severe radiation sensitivity, interfering with the standard techniques of single-crystal X-ray diffraction^2,3 and electron microdiffraction^4–11. Here we demonstrate small-molecule serial femtosecond X-ray crystallography (smSFX) for the determination of material crystal structures from microcrystals. We subjected microcrystalline suspensions to X-ray free-electron laser radiation^12,13 and obtained thousands of randomly oriented diffraction patterns. We determined unit cells by aggregating spot-finding results into high-resolution powder diffractograms. After indexing the sparse serial patterns by a graph theory approach¹⁴, the resulting datasets can be solved and refined using standard tools for single-crystal diffraction data^15–17. We describe the ab initio structure solutions of mithrene (AgSePh)^18–20, thiorene (AgSPh) and tethrene (AgTePh), of which the latter two were previously unknown structures. In thiorene, we identify a geometric change in the silver–silver bonding network that is linked to its divergent optoelectronic properties²⁰. We demonstrate that smSFX can be applied as a general technique for structure determination of beam-sensitive microcrystalline materials at near-ambient temperature and pressure.

In the last decade, halide perovskites have seen tremendous advancements, primarily in the field of solar cells and light-emitting diodes (LEDs). However, their remarkable optical and electronic properties are not only amenable for their use in solar cells and LEDs; as they can also be used for several other applications. While most research has focused on lead-based perovskites, their lead-free counterparts offer several potential advantages. Some of these advantages include reduced toxicity, improved stability, and a more diverse chemistry. Herein, we review some of the ‘other’ most notable applications of lead-free perovskites, including their use as photodetectors, photocatalysts, memristors, field-effect transistors, among others. We conclude by highlighting some of the pressing challenges and promising research avenues in the field.