Ceratti Davide Raffaele, Tenne Ron, Bartezzaghi Andrea, Cremonesi Llorenç, Segev Lior, Kalchenko Vyacheslav, Oron Dan, Potenza Marco Alberto Carlo, Hodes Gary, Cahen David
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 7610001, Israel.
CNRS, UMR 9006, IPVF, Institut Photovoltaïque d'Ile-de-France, 18 Boulevard Thomas Gobert, Palaiseau, 91120, France.
Adv Mater. 2022 Sep;34(35):e2110239. doi: 10.1002/adma.202110239. Epub 2022 Jul 29.
The future of halide perovskites (HaPs) is beclouded by limited understanding of their long-term stability. While HaPs can be altered by radiation that induces multiple processes, they can also return to their original state by "self-healing." Here two-photon (2P) absorption is used to effect light-induced modifications within MAPbI single crystals. Then the changes in the photodamaged region are followed by measuring the photoluminescence, from 2P absorption with 2.5 orders of magnitude lower intensity than that used for photodamaging the MAPbI . After photodamage, two brightening and one darkening process are found, all of which recover but on different timescales. The first two are attributed to trap-filling (the fastest) and to proton-amine-related chemistry (the slowest), while photodamage is attributed to the lead-iodide sublattice. Surprisingly, while after 2P-irradiation of crystals that are stored in dry, inert ambient, photobrightening (or "light-soaking") occurs, mostly photodarkening is seen after photodamage in humid ambient, showing an important connection between the self-healing of a HaP and the presence of H O, for long-term steady-state illumination, practically no difference remains between samples kept in dry or humid environments. This result suggests that photobrightening requires a chemical-reservoir that is sensitive to the presence of H O, or possibly other proton-related, particularly amine, chemistry.
卤化物钙钛矿（HaPs）的未来因对其长期稳定性的了解有限而蒙上阴影。虽然HaPs会因诱导多种过程的辐射而发生改变，但它们也能通过“自我修复”恢复到原始状态。在这里，双光子（2P）吸收被用于在MAPbI单晶内实现光诱导改性。然后，通过测量光致发光来跟踪光损伤区域的变化，该光致发光来自强度比用于损伤MAPbI的光低2.5个数量级的2P吸收。光损伤后，发现了两个变亮过程和一个变暗过程，所有这些过程都会恢复，但时间尺度不同。前两个过程分别归因于陷阱填充（最快）和与质子 - 胺相关的化学作用（最慢），而光损伤归因于碘化铅亚晶格。令人惊讶的是，虽然在干燥、惰性环境中储存的晶体经2P辐照后会发生光致变亮（或“光浸泡”），但在潮湿环境中光损伤后大多出现光致变暗，这表明HaP的自我修复与H₂O的存在之间存在重要联系，对于长期稳态光照，保存在干燥或潮湿环境中的样品之间几乎没有差异。这一结果表明，光致变亮需要一个对H₂O的存在敏感的化学库，或者可能是其他与质子相关的，特别是胺的化学作用。
