Singh Pallavi, Ceratti Davide Raffaele, Soffer Yahel, Bera Sudipta, Feldman Yishay, Elbaum Michael, Oron Dan, Cahen David, Hodes Gary
Dept. of Molecular Chem. & Materials Science, Weizmann Institute of Science, Rehovot 7610001, Israel.
CNRS, Chimie ParisTech, Institut de Recherche de Chimie Paris, Physical Chemistry of Surfaces Group, PSL University, 11 rue Pierre et Marie Curie, Paris 75005, France.
J Phys Chem C Nanomater Interfaces. 2024 Nov 20;128(47):19999-20008. doi: 10.1021/acs.jpcc.4c06090. eCollection 2024 Nov 28.
Self-healing materials can become game changers for developing sustainable (opto)electronics. APbX halide (=X) perovskites, HaPs, have shown a remarkable ability to self-heal damage. While we demonstrated self-healing in pure HaP compounds, in single crystals, and in polycrystalline thin films (as used in most devices), HaP compositions with multiple A (and X) constituents are preferred for solar cells. We now show self-healing in mixed A HaPs. Specifically, if at least 15 atom % of the methylammonium (MA) A cation is substituted for by guanidinium (Gua) or acetamidinium (AA), then the self-healing rate after damage is enhanced. In contrast, replacing MA with dimethylammonium (DMA), comparable in size to Gua or AA, does not alter this rate. Based on the times for self-healing, we infer that the rate-determining step involves short-range diffusion of A and/or Pb cations and that the self-healing rate correlates with the strain in the material, the A cation dipole moment, and H-bonding between A and I. These insights may offer clues for developing a detailed self-healing mechanism and understanding the kinetics to guide the design of self-healing materials. Fast recovery kinetics are important from the device perspective, as they allow complete recovery in devices during operation or when switched off (LEDs)/in the dark (photovoltaics).
自修复材料可能会成为发展可持续（光）电子学的变革者。APbX卤化物（X = Cl、Br、I）钙钛矿（HaPs）已显示出显著的自修复损伤能力。虽然我们已在纯HaP化合物、单晶以及多晶薄膜（大多数器件中所使用的）中证明了自修复现象，但太阳能电池更倾向于使用具有多种A（和X）成分的HaP组合物。我们现在展示了混合A的HaP中的自修复现象。具体而言，如果至少15原子%的甲铵（MA）A阳离子被胍（Gua）或乙脒（AA）取代，那么损伤后的自修复速率会提高。相比之下，用与Gua或AA尺寸相当的二甲铵（DMA）取代MA，并不会改变该速率。基于自修复时间，我们推断速率决定步骤涉及A和/或Pb阳离子的短程扩散，并且自修复速率与材料中的应变、A阳离子偶极矩以及A和I之间的氢键有关。这些见解可能为建立详细的自修复机制以及理解动力学以指导自修复材料的设计提供线索。从器件角度来看，快速恢复动力学很重要，因为它们能使器件在运行期间或关闭时（发光二极管）/在黑暗中（光伏器件）实现完全恢复。
