For the first time, hybrid metal halide perovskites with atomic-scale resolution have been imaged, providing new insights into these wonder materials.
The group of researchers from Oxford's departments of Materials* and Physics share their findings about the materials' remarkable self-healing powers in Science. Their findings further our critical understanding of how such perovskites work, and are an essential step close to the commercial production of perovskite solar cells.
The team used low-dose scanning tranmission electron microscopy (STEM) imaging to determine the microstructure of thin hybrid perovskite films. Thermally evaporated thin films of formamidinium and methylammonium lead triiodide (FAPbl3 and MAPbl3 respectively) were examined on ultrathin carbon-coated copper TEM grids to reveal the nature of boundaries, defects, and decomposition pathways.
The findings provide an atomic-level understanding of the technologically important class of hybrid lead halide perovskites, revealing several mechanisms that underpin their remarkable performance. The highly adaptive nature of the perovskite structure upon organic cation loss yields exceptional regenerative properties of partly degraded material. The observation on coherent perovskite interfaces with Pbl2 explains the barely diminished optoelectronic performance upon such precursor inclusions, while sharp interfaces between perovskite grains grant a benign nature.
Such atomically localised information enables the targeted design of methods to eliminate defects and optimise interfaces in these materials.