Researchers at the Weizmann Institute of Science have found that in halide perovskites, creating defects takes more effort than restoring order. This finding may explain the remarkable properties of halide perovskites and help develop a new approach to controlling the properties of these and other materials.
Much about Halide perovskites still puzzles researchers; in particular, it has been unclear why they can contain relatively few defects, on the order of 1010 per cubic centimeter (that is, one defect for every trillion atoms, instead of the one to a hundred for every million, as in regular semiconductors). This concentration of defects rivals that of germanium crystals, among the cleanest solid-state man-made materials. Getting close to such a low defect concentration in the semiconductors used in today’s electronic devices requires enormous effort and ingenuity. In contrast, halide perovskites can be produced within a fraction of a second by mixing simple chemical salt solutions at near room temperature.