Role of Methylammonium Orientation in Ion Diffusion and Current–Voltage Hysteresis in the CH3NH3PbI3 Perovskite,ACS Energy Letters

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Role of Methylammonium Orientation in Ion Diffusion and Current–Voltage Hysteresis in the CH3NH3PbI3 Perovskite
ACS Energy Letters ( IF 19.3 ) Pub Date : 2017-08-10 00:00:00 , DOI: 10.1021/acsenergylett.7b00659
Chuan-Jia Tong _{1,

2} , Wei Geng ₁ , Oleg V. Prezhdo ₂ , Li-Min Liu ₁

Affiliation

Hybrid organic–inorganic perovskites, and particularly CH₃NH₃PbI₃ (MAPbI₃), have emerged as a new generation of photovoltaic devices due to low cost and superior performance. The performance is strongly influenced by current–voltage hysteresis that arises due to ion migration, and the challenge remains how to suppress the ion migration and hysteresis. Our first-principles calculations demonstrate that the energy barriers to diffusion of the I^–, MA⁺, and Pb²⁺ ions are greatly affected by dipole moments of the MA species. The energy barriers of the most mobile I^– ion range from 0.06 to 0.65 eV, depending on MA orientation. The positively charged MA⁺ and Pb²⁺ ions diffuse along the dipole direction, while the negatively charged I^– ion strongly prefers to diffuse against the dipole direction. By influencing ion migration, the arrangement of MA molecules can effectively modulate the current–voltage hysteresis intensity. The current work contributes to the fundamental understanding of the microscopic mechanism of ion migration in MAPbI₃ and suggests means to suppress the hysteresis effect and optimize perovskite performance. By demonstrating in detail how the arrangement of the organic molecules can efficiently influence ion migration and, hence, amplitude of the current–voltage hysteresis, our results suggest that the hysteresis effect can be suppressed and the long-term performance of perovskites can be improved, if the organic molecules are arranged and stabilized in an antiferroelectric order.

中文翻译：

CH ₃ NH ₃ PbI ₃钙钛矿中甲基铵取向在离子扩散和电流电压滞后中的作用

杂化有机-无机钙钛矿，和特别是CH ₃ NH ₃碘化铅₃（MAPbI ₃），已成为新一代的光伏器件由于低成本和优异的性能。由于离子迁移而产生的电流-电压磁滞会严重影响性能，而如何抑制离子迁移和磁滞仍是挑战。我们的第一原理计算表明，到我的扩散能量壁垒^-，MA ⁺和Pb ²⁺离子有很大的影响的MA物种的偶极矩。移动性最大的能源壁垒^–离子的范围从0.06到0.65 eV，具体取决于MA方向。带正电的MA ⁺和Pb ²⁺离子沿偶极方向扩散，而带负电荷的我^-离子强烈倾向于扩散对偶极方向。通过影响离子迁移，MA分子的排列可以有效地调节电流-电压磁滞强度。当前的工作有助于对MAPbI ₃中离子迁移的微观机理的基本理解。并提出了抑制磁滞效应和优化钙钛矿性能的方法。通过详细说明有机分子的排列方式如何有效地影响离子迁移并因此影响电流-电压磁滞的幅度，我们的结果表明，可以抑制磁滞效应并可以改善钙钛矿的长期性能，如果有机分子以反铁电顺序排列和稳定。

更新日期：2017-08-10

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