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Photoinduced Phase Segregation in Mixed Halide Perovskites: Thermodynamic and Kinetic Aspects of Cl–Br Segregation
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2020-10-13 , DOI: 10.1002/adom.202001440 Junsang Cho 1 , Prashant V. Kamat 1, 2, 3
Advanced Optical Materials ( IF 8.0 ) Pub Date : 2020-10-13 , DOI: 10.1002/adom.202001440 Junsang Cho 1 , Prashant V. Kamat 1, 2, 3
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Suppression of halide ion mobility remains a key issue in defining the device performances and stability of perovskite solar cells. The halide ion migration is facilitated by the lattice-distortion-mediated halide vacancy and hence dictated by the polarizability (or rigidity) of the halide sublattice and framework. Photoinduced halide ion segregation and dark recovery of MAPb(Cl0.5Br0.5)3 films are now probed. The temperature dependence of the rate constants of segregation and dark remixing allow to determine the activation energy barriers (Ea) for photosegregation (38 kJ mol−1) and dark recovery (42 kJ mol−1). A comparison of the segregation activation energy (Ea) and excitation intensity threshold between MAPb(Cl0.5Br0.5)3 and MAPb(Br0.5I0.5)3 films reflects that the presence of Cl stabilizes mixed halide composition. The thermodynamic stabilization is attributed to the formation of more rigid [PbX6]4− frameworks with an increased barrier for halide ion migration. The thermodynamic rationale behind the intriguing halide ion mobility offers a fundamental insight into the role of Cl and design principle of perovskite solar cells with improved efficiency and long-term stability.
中文翻译：
混合卤化物钙钛矿中的光致相分离：Cl-Br 分离的热力学和动力学方面
抑制卤化物离子迁移率仍然是定义钙钛矿太阳能电池器件性能和稳定性的关键问题。卤化物离子迁移由晶格畸变介导的卤化物空位促进，因此由卤化物亚晶格和框架的极化率（或刚性）决定。现在探测了 MAPb(Cl 0.5 Br 0.5 ) 3薄膜的光致卤离子分离和暗恢复。分离和暗再混合的速率常数的温度依赖性允许确定光分离（38 kJ mol -1）和暗恢复（42 kJ mol -1）的活化能垒（E a）。偏析活化能的比较（E a ) 和MAPb(Cl 0.5 Br 0.5 ) 3和MAPb(Br 0.5 I 0.5 ) 3膜之间的激发强度阈值反映了Cl的存在稳定了混合卤化物组合物。热力学稳定性归因于形成更刚性的 [PbX 6 ] 4-骨架，并增加了卤化物离子迁移的屏障。有趣的卤化物离子迁移率背后的热力学原理为了解 Cl 的作用和钙钛矿太阳能电池的设计原理提供了基本见解，具有更高的效率和长期稳定性。
更新日期：2020-10-13
中文翻译：
混合卤化物钙钛矿中的光致相分离：Cl-Br 分离的热力学和动力学方面
抑制卤化物离子迁移率仍然是定义钙钛矿太阳能电池器件性能和稳定性的关键问题。卤化物离子迁移由晶格畸变介导的卤化物空位促进，因此由卤化物亚晶格和框架的极化率（或刚性）决定。现在探测了 MAPb(Cl 0.5 Br 0.5 ) 3薄膜的光致卤离子分离和暗恢复。分离和暗再混合的速率常数的温度依赖性允许确定光分离（38 kJ mol -1）和暗恢复（42 kJ mol -1）的活化能垒（E a）。偏析活化能的比较（E a ) 和MAPb(Cl 0.5 Br 0.5 ) 3和MAPb(Br 0.5 I 0.5 ) 3膜之间的激发强度阈值反映了Cl的存在稳定了混合卤化物组合物。热力学稳定性归因于形成更刚性的 [PbX 6 ] 4-骨架，并增加了卤化物离子迁移的屏障。有趣的卤化物离子迁移率背后的热力学原理为了解 Cl 的作用和钙钛矿太阳能电池的设计原理提供了基本见解，具有更高的效率和长期稳定性。
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