Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O2 As a Molecular Probe,Helvetica Chimica Acta

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Optimizing the Atomic Layer Deposition of Alumina on Perovskite Nanocrystal Films by Using O2 As a Molecular Probe
Helvetica Chimica Acta ( IF 1.5 ) Pub Date : 2020-05-07 , DOI: 10.1002/hlca.202000055
Seryio Saris ₁ , Sanduni T. Dona ₁ , Valerie Niemann ₁ , Anna Loiudice ₁ , Raffaella Buonsanti ₁

Affiliation

Encapsulation methods have shown to be effective in imparting improved stability to metal‐halide perovskite nanocrystals (NCs). Atomic layer deposition (ALD) of metal oxides is one of the promising approaches for such encapsulation, yet better control on the process parameters are required to achieve viable lifetimes for several optoelectronic and photocatalytic applications. Herein, we optimize the ALD process of amorphous aluminum oxide (AlO_x) as an encapsulating layer for CsPbBr₃ NC thin films by using oxygen (O₂) as a molecular diffusion probe to assess the uniformity of the deposited AlO_x layer. When O₂ reaches the NC surface, it extracts the photogenerated electrons, thus quenching the PL of the CsPbBr₃ NCs. As the quality of the ALD layer improves, less quenching is expected. We compare three different ALD deposition modes. We find that the low temperature/high temperature and the exposure modes improve the quality of the alumina as a gas barrier when compared with the low temperature mode. We attribute this result to a better diffusion of the ALD precursor throughout the NC film. We propose the low temperature/high temperature as the most suitable mode for future implementation of multilayered coatings.

中文翻译：

以O2为分子探针优化钙钛矿纳米晶膜上氧化铝原子层的沉积

封装方法已证明可有效提高金属卤化物钙钛矿纳米晶体（NC）的稳定性。金属氧化物的原子层沉积（ALD）是这种封装的一种有前途的方法，但是需要对工艺参数进行更好的控制，以实现几种光电和光催化应用的可行寿命。在这里，我们通过使用氧（O ₂）作为分子扩散探针来评估沉积的AlO _x层的均匀性，优化了无定形氧化铝（AlO _x）作为CsPbBr ₃ NC薄膜封装层的ALD工艺。当O ₂到达NC表面时，它将提取光生电子，从而淬灭CsPbBr的PL_3个NC。随着ALD层质量的提高，预计淬灭会更少。我们比较了三种不同的ALD沉积模式。我们发现，与低温模式相比，低温/高温和暴露模式提高了氧化铝作为阻气层的质量。我们将此结果归因于ALD前体在整个NC膜中的更好扩散。我们提出低温/高温是将来多层涂层实施的最合适方式。

更新日期：2020-05-07

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