中国物理B ›› 2019, Vol. 28 ›› Issue (5): 56402-056402.doi: 10.1088/1674-1056/28/5/056402

• CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES • 上一篇    下一篇

Surface stabilized cubic phase of CsPbI3 and CsPbBr3 at room temperature

Feng Yang(杨凤), Cong Wang(王聪), Yuhao Pan(潘宇浩), Xieyu Zhou(周谐宇), Xianghua Kong(孔祥华), Wei Ji(季威)   

  1. Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
  • 收稿日期:2019-03-11 修回日期:2019-03-21 出版日期:2019-05-05 发布日期:2019-05-05
  • 通讯作者: Wei Ji E-mail:wji@ruc.edu.cn
  • 基金资助:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 91433103, 11622437, and 61674171), the Fundamental Research Funds for the Central Universities of China, the Research Funds of Renmin University of China (Grant Nos. 16XNLQ01 and 19XNH065), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB30000000).

Surface stabilized cubic phase of CsPbI3 and CsPbBr3 at room temperature

Feng Yang(杨凤), Cong Wang(王聪), Yuhao Pan(潘宇浩), Xieyu Zhou(周谐宇), Xianghua Kong(孔祥华), Wei Ji(季威)   

  1. Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
  • Received:2019-03-11 Revised:2019-03-21 Online:2019-05-05 Published:2019-05-05
  • Contact: Wei Ji E-mail:wji@ruc.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 91433103, 11622437, and 61674171), the Fundamental Research Funds for the Central Universities of China, the Research Funds of Renmin University of China (Grant Nos. 16XNLQ01 and 19XNH065), and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB30000000).

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摘要：

Inorganic halide perovskites CsPbX3 (X=I, Br) have attracted tremendous attention in solar cell applications. However, the bulk form of the cubic phase CsPbX3, which offers moderate direct bandgaps, is metastable at room temperature and tends to transform into a tetragonal or orthorhombic phase. Here, our density functional theory calculation results found that the surface energies of the cubic phase are smaller than those of the orthorhombic phase, although the bulk counterpart of the cubic phase is less stable than that of the orthorhombic phase. These results suggest a surface stabilization strategy to maintain the stability of the cubic phase at room temperature that an enlarged portion of surfaces shall change the relative stability of the two phases in nanostructured CsPbX3. This strategy, which may potentially solve the long-standing stability issue of cubic CsPbX3, was demonstrated to be feasible by our calculations in zero-, one-, and two-dimensional nanostructures. In particular, confined sizes from few to tens of nanometers could keep the cubic phase as the most thermally favored form at room temperature. Our predicted values in particular cases, such as the zero-dimensional form of CsPbI3, are highly consistent with experimental values, suggesting that our model is reasonable and our results are reliable. These predicted critical sizes give the upper and lower limits of the confined sizes, which may guide experimentalists to synthesize these nanostructures and promote likely practical applications such as solar cells and flexible displays using CsPbX3 nanostructures.

关键词: inorganic perovskite solar cell, thermal stability, surface energy, nanowire, quantum dot, nano-plate

Abstract:

Inorganic halide perovskites CsPbX3 (X=I, Br) have attracted tremendous attention in solar cell applications. However, the bulk form of the cubic phase CsPbX3, which offers moderate direct bandgaps, is metastable at room temperature and tends to transform into a tetragonal or orthorhombic phase. Here, our density functional theory calculation results found that the surface energies of the cubic phase are smaller than those of the orthorhombic phase, although the bulk counterpart of the cubic phase is less stable than that of the orthorhombic phase. These results suggest a surface stabilization strategy to maintain the stability of the cubic phase at room temperature that an enlarged portion of surfaces shall change the relative stability of the two phases in nanostructured CsPbX3. This strategy, which may potentially solve the long-standing stability issue of cubic CsPbX3, was demonstrated to be feasible by our calculations in zero-, one-, and two-dimensional nanostructures. In particular, confined sizes from few to tens of nanometers could keep the cubic phase as the most thermally favored form at room temperature. Our predicted values in particular cases, such as the zero-dimensional form of CsPbI3, are highly consistent with experimental values, suggesting that our model is reasonable and our results are reliable. These predicted critical sizes give the upper and lower limits of the confined sizes, which may guide experimentalists to synthesize these nanostructures and promote likely practical applications such as solar cells and flexible displays using CsPbX3 nanostructures.

Key words: inorganic perovskite solar cell, thermal stability, surface energy, nanowire, quantum dot, nano-plate

中图分类号:  (Structural transitions in nanoscale materials)

  • 64.70.Nd
71.15.Mb (Density functional theory, local density approximation, gradient and other corrections) 84.60.Jt (Photoelectric conversion)