Commercialization is widely believed to be achievable for metal halide perovskite solar cells with high efficiency and low fabrication cost. However, stability remains a key obstacle for them to compete with established photovoltaic technologies. The pho
platinum). The rare earths are actually some of the best samples, being mostly chips rather than powders. Scandium is particularly attractive, as are the alkali metals in their shiny mini-tubes. There are surprisingly large amounts of cesium, rubidium, and bromine. (I should say ...