In the search for more efficient and sustainable energy generation methods, a class of materials called metal halide perovskites have shown great promise. In the few years since their discovery, novel solar cells based on these materials have already achieved efficiencies comparable to commercial silicon solar cells.
This article has been reviewed according to Science X's editorial process and policies . Editors have highlighted the following attributes while ensuring the content's credibility: Probing the chemical and crystallographic nanomorphology of metal halide perovskites with terahertz near-field spectroscopy. Credit: Nature Photonics (2024). DOI: 10.1038/s41566-024-01476-1 Yet, perovskite solar cells offer significant advantages over silicon: Their manufacturing and energy costs are lower, as they can be produced using cost-effective coating processes. Moreover, their flexibility and lightweight nature allows for application on a wide range of surfaces, from portable electronics to innovative building facades. But how does a solar cell actually work? Sunlight, which consists of individual light quanta called photons, is absorbed in the solar cell. The photons transfer their energy to electrons, lifting them to higher-energy states where they are free to move. The free electrons are then extracted at electrical contacts and converted into usable electrical energy. The efficiency of a solar cell thus depends crucially on how effectively these short-lived charge carriers can travel through the material to reach the contacts before decaying. To further optimize solar cells strategically, it is essential to understand exactly how this transport takes place, including the pathways electrons take and what hinders their movement. This challenging task has now been accomplished by researchers at the University of Regensburg led by Prof. Dr. Rupert Huber with a new type of ultrafast microscope using tailor-made samples from Prof. Dr. Michael Johnston (Oxford University). The team managed to generate free electrons and track their diffusion on ultrashort time scales. Their findings are published in the journal Nature Photonics. In perovskite solar cells, this constitutes a particular challenge, as they are not homogeneous but consist of many…