Role of surface termination and quantum size in α-CsPbX3 (X = Cl, Br, I) 2D nanostructures for solar light harvesting,Physical Chemistry Chemical Physics

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Role of surface termination and quantum size in α-CsPbX3 (X = Cl, Br, I) 2D nanostructures for solar light harvesting
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2021-1-16 , DOI: 10.1039/d0cp06245f
Giovanni Di Liberto _{1,

2,

3,

4} , Ornella Fatale _{1,

2,

3,

4,

5} , Gianfranco Pacchioni _{1,

2,

3,

4}

Affiliation

α-CsPbX₃ (X = Cl, Br, I) 2D nanostructures are widely used in solar cells, photocatalysis and photovoltaic applications, mainly because of their high efficiency in the conversion of solar energy. Based on hybrid Density Functional Theory (DFT) calculations we consider two aspects, (a) the role of surface termination, and (b) that of quantum size (thickness) of the 2D slabs. We show that the surface termination is a key aspect in determining the electronic properties. For the (001) surface of α-CsPbX₃ perovskites there are two possible terminations, with similar stabilities but different positions of the band edges. In general, the band edges of the (110) surfaces, with the X-terminated surface being the most stable one, are lower in energy than the (001) ones. These conclusions are very important for the design of efficient heterostructures for solar light harvesting. Furthermore, the properties of α-CsPbX₃ 2D nanostructures can be tuned by varying the thickness. We present a general model to predict quantum size effects of α-CsPbX₃ from ultrathin films (3–5 atomic layers) to the bulk. Finally, based on calculated electronic properties of CsPbX₃ (and TiO₂ surfaces), we estimate a type-II alignment in composites such as CsPbX₃/TiO₂, favourable for electron migration from the perovskite to TiO₂. These results can help the rational design of halide perovskite nanostructures for solar energy harvesting, in particular by interfacing 2D materials with specific surfaces and terminations.

中文翻译：

表面终止和量子尺寸在α-CsPbX3（X = Cl，Br，I）2D纳米结构中的作用，用于太阳光收集

α-CsPbX ₃（X =氯，溴，I）的2D纳米结构被广泛用于太阳能电池，光催化和光电应用，主要是因为在太阳能转换它们的高效率。基于混合密度泛函理论（DFT）计算，我们考虑了两个方面，（a）表面终止的作用，（b）二维平板的量子尺寸（厚度）。我们表明，表面终止是确定电子特性的关键方面。为的（001）面α-CsPbX ₃钙钛矿有两种可能的终结点，具有相似的稳定性，但带边缘的位置不同。通常，（110）表面的能带边缘（以X端接的表面最稳定）的能量要比（001）表面的能带能量低。这些结论对于设计有效的太阳能采光异质结构非常重要。此外，α-CsPbX的属性_3个2D纳米结构可通过改变厚度来调谐。我们提出了一个一般的模型来预测α-CsPbX的量子晶粒尺寸效应₃从超薄薄膜（3-5个原子层）发生本体。最后，基于计算出的CsPbX ₃（和TiO ₂表面）的电子性能，我们估算了复合材料（如CsPbX）中的II型排列₃ / TiO₂，有利于电子从钙钛矿迁移到TiO₂。这些结果可以帮助合理设计卤化钙钛矿纳米结构用于太阳能收集，特别是通过将2D材料与特定表面和端接连接起来。

更新日期：2021-01-22

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