Origins of the Pressure-Induced Phase Transition and Metallization in the Halide Perovskite (CH3NH3)PbI3,ACS Energy Letters

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Origins of the Pressure-Induced Phase Transition and Metallization in the Halide Perovskite (CH3NH3)PbI3
ACS Energy Letters ( IF 19.3 ) Pub Date : 2020-05-19 , DOI: 10.1021/acsenergylett.0c00772
Jung-Hoon Lee _{1,

2,

3} , Adam Jaffe ₄ , Yu Lin ₅ , Hemamala I. Karunadasa _{4,

5} , Jeffrey B. Neaton _{1,

2,

6}

Affiliation

Hybrid halide perovskites are promising for applications because of their favorable optoelectronic properties and low cost. Here we investigate the effects of hydrostatic pressure on the structural and electronic properties of (MA)PbI₃ (MA = CH₃NH₃⁺) using first-principles density functional theory calculations. Our calculations predict that at a pressure of 0.23 GPa, the orthorhombic Fmmm phase becomes unstable with respect to a cubic Im3̅ phase, in good agreement with room-temperature experiments (∼0.3 GPa). At higher pressures, about 6 GPa, we predict the onset of pronounced intra- and interoctahedral distortions. This symmetry lowering leads to the introduction of I 5p–I 5p* antibonding and Pb 6p–Pb 6p bonding character into the valence band maximum (VBM) and the conduction band minimum (CBM) states, respectively. We find this change in bond character explains the evolution of the VBM and CBM states under compression, trends that ultimately lead to metallization at significantly higher pressures.

中文翻译：

卤化物钙钛矿（CH ₃ NH ₃）PbI _3中压力诱导的相变和金属化的起源

杂化卤化物钙钛矿具有良好的光电性能和低成本，因此有望用于应用。在这里，我们使用第一原理密度泛函理论计算研究静水压力对（MA）PbI ₃（MA = CH ₃ NH ₃⁺）的结构和电子性能的影响。我们的计算预测，在0.23 GPa的压力下，正交立方Fmmm相相对于立方Im变得不稳定3̅相，与室温实验（〜0.3 GPa）吻合良好。在大约6 GPa的较高压力下，我们可以预测八面体和八面体之间明显的变形。这种对称性降低导致分别将I 5p–I 5p *反键和Pb 6p–Pb 6p键性引入价带最大值（VBM）和导带最小值（CBM）状态。我们发现这种键合特性的变化解释了压缩状态下VBM和CBM状态的演变，这种趋势最终导致在明显更高的压力下金属化。

更新日期：2020-07-10

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