Octahedron rotation evolution in 2D perovskites and its impact on optoelectronic properties: the case of Ba–Zr–S chalcogenides,Materials Horizons

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Octahedron rotation evolution in 2D perovskites and its impact on optoelectronic properties: the case of Ba–Zr–S chalcogenides
Materials Horizons ( IF 12.2 ) Pub Date : 2020-08-24 , DOI: 10.1039/d0mh01092h
Chen Ming _{1,

2,

3,

4,

5} , Ke Yang _{6,

7,

8,

9,

10} , Hao Zeng _{6,

10,

11,

12,

13} , Shengbai Zhang _{6,

7,

8,

9,

10} , Yi-Yang Sun _{1,

2,

3,

4,

5}

Affiliation

Octahedron rotation (OR) is a unique structural feature in most perovskite materials. During dimensional reduction from bulk to two-dimensional (2D) perovskites, how the OR pattern evolves is still an open question. Here, we employ an adapted Glazer's notation from bulk perovskites to systematically study the structural evolution of 2D perovskites by fully considering the possible OR patterns. Applying this approach to the 2D Ba–Zr–S system, we establish the relationship between the OR pattern and slab thickness. It is found that as the thickness decreases, the OR pattern undergoes a transition by suppressing out-of-plane rotations. The OR in 2D chalcogenide perovskites could result in an anti-confinement effect, i.e., reducing the band gap to even below that of the bulk by countering the quantum confinement effect. In addition, we show that the Ba–Zr–S 2D perovskites exhibit reasonable electron mobility of ∼150 cm² V⁻¹ s⁻¹ and large exciton binding energy of ∼0.9 eV. Combining the slab thickness and strain as effective knobs for widely tuning the electronic structure, we suggest the 2D chalcogenide perovskites as promising optoelectronic materials.

中文翻译：

二维钙钛矿中八面体旋转演化及其对光电性能的影响：以Ba–Zr–S硫属化物为例

八面体旋转（OR）是大多数钙钛矿材料的独特结构特征。在将体积从钙钛矿减少到二维（2D）钙钛矿的过程中，OR模式如何演变仍然是一个悬而未决的问题。在这里，我们从大量钙钛矿中采用了适应性的Glazer表示法，通过充分考虑可能的OR模式来系统地研究2D钙钛矿的结构演变。将这种方法应用于二维Ba–Zr–S系统，我们建立了OR模式与板坯厚度之间的关系。发现随着厚度减小，OR图案通过抑制平面外旋转而经历过渡。二维硫属元素钙钛矿中的OR可能导致抗限制作用，即通过抵消量子限制效应，将带隙减小到甚至低于本体的带隙。另外，我们表明Ba-Zr-S 2D钙钛矿表现出约150 cm ² V ^-1 s ^-1的合理电子迁移率和约0.9 eV的大激子结合能。结合平板厚度和应变作为有效调节电子结构的有效旋钮，我们建议将二维硫族化物钙钛矿用作有前途的光电材料。

更新日期：2020-09-08

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