Unveiling the Intrinsic Structure and Intragrain Defects of Organic-Inorganic Hybrid Perovskites by Ultralow Dose Transmission Electron Microscopy.
basic_science · Level V
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- Record sourced from PubMed, PMID 36780501.
- Also identified by DOI 10.1002/adma.202211207.
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Abstract
Transmission electron microscopy (TEM) is a powerful tool for unveiling the structural, compositional, and electronic properties of organic-inorganic hybrid perovskites (OIHPs) at the atomic to micrometer length scales. However, the structural and compositional instability of OIHPs under electron beam radiation results in misunderstandings of the microscopic structure-property-performance relationship in OIHP devices. Here, ultralow dose TEM is utilized to identify the mechanism of the electron-beam-induced changes in OHIPs and clarify the cumulative electron dose thresholds (critical dose) of different commercially interesting state-of-the-art OIHPs, including methylammonium lead iodide (MAPbI<sub>3</sub> ), formamidinium lead iodide (FAPbI<sub>3</sub> ), FA<sub>0.83</sub> Cs<sub>0.17</sub> PbI<sub>3</sub> , FA<sub>0.15</sub> Cs<sub>0.85</sub> PbI<sub>3</sub> , and MAPb<sub>0.5</sub> Sn<sub>0.5</sub> I<sub>3</sub> . The critical dose is related to the composition of the OIHPs, with FA<sub>0.15</sub> Cs<sub>0.85</sub> PbI<sub>3</sub> having the highest critical dose of ≈84 e Å<sup>-2</sup> and FA<sub>0.83</sub> Cs<sub>0.17</sub> PbI<sub>3</sub> having the lowest critical dose of ≈4.2 e Å<sup>-2</sup> . The electron beam irradiation results in the formation of a superstructure with ordered I and FA vacancies along <110><sub>c</sub> , as identified from the three major crystal axes in cubic FAPbI<sub>3</sub> , <100><sub>c</sub> , <110><sub>c</sub> , and <111><sub>c</sub> . The intragrain planar defects in FAPbI<sub>3</sub> are stable, while an obvious modification is observed in FA<sub>0.83</sub> Cs<sub>0.17</sub> PbI<sub>3</sub> under continuous electron beam exposure. This information can serve as a guide for ensuring a reliable understanding of the microstructure of OIHP optoelectronic devices by TEM.