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Guanidinium Substitution Improves Self-Healing and Photodamage Resilience of MAPbI3

Year: 2024

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide Self-healing materials can become game changers for developing sustainable (opto)electronics. APbX 3 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 2+ 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).

Source: The Journal of Physical Chemistry C

DOI: 10.1021/acs.jpcc.4c06090