Hybrid Perovskites with Larger Organic Cations Reveal Autocatalytic Degradation Kinetics and Increased Stability under Light
Hybrid Perovskites with Larger Organic Cations Reveal Autocatalytic Degradation Kinetics and Increased Stability under Light
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DOI：
10.1021/acs.inorgchem.0c01133
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发表时间：
2020-09-08
影响因子：
4.6
通讯作者：
Venkataraman, D.
中科院分区：
文献类型：
--
作者：
Ellis, Christie L. C.;Javaid, Hamza;Venkataraman, D.
杂化有机无机钙钛矿作为光伏器件的活性材料显示出令人难以置信的前景，但它们对光的不稳定性仍然是实现这些应用的重大障碍。改变有机阳离子已被证明会影响光诱导的降解。作为提高这些材料稳定性的策略，我们用三种更大的有机铵阳离子：咪唑鎓、二甲基铵和胍鎓，取代了典型的甲基铵碘化铅（MAPbI3）杂化有机无机钙钛矿中不同百分比的甲基铵离子。我们能够合成具有与 MAPbI3 相同的 3D 钙钛矿结构的杂化有机无机钙钛矿，并取代高达 20-30% 的较大离子。这些取代的杂化有机无机钙钛矿保留了类似的光电特性。我们发现 MAPbI3 及其取代衍生物的光诱导降解是自催化的，并且我们计算了降解的速率系数。所有取代的杂化有机无机钙钛矿的光诱导降解速度都比 MAPbI3 慢，在所有取代百分比高达 20% 的情况下，降解率系数降低了 62%。这项工作提供了证据，表明高比例的各种大铵阳离子可以取代杂化有机无机钙钛矿晶格，而不损害其所需的光电性能。深入了解光诱导降解的自催化机制对于设计额外的策略来提高杂化有机无机钙钛矿的稳定性非常有价值。我们还提供了关于尺寸以外的因素（例如氢键）如何影响材料稳定性的见解。总的来说，我们已经证明，用甲基铵离子取代 MAPbI3 中较大的咪唑鎓、二甲基铵和胍鎓阳离子是通过减缓光诱导降解速率来创建稳定的杂化有机无机钙钛矿衍生物的有效策略。
Hybrid organic inorganic perovskites have shown incredible promise as active materials for photovoltaic devices, but their instability to light remains a significant roadblock in realizing these applications. Changing the organic cation has been shown to affect light-induced degradation. As a strategy for increasing the stability of these materials, we replaced varying percentages of methylammonium ion in the archetypical methylammonium lead iodide (MAPbI3) hybrid organic inorganic perovskite with three significantly larger organic ammonium cations: imidazolium, dimethylammonium, and guanidinium. We were able to synthesize hybrid organic inorganic perovskites with the same 3D perovskite structure as MAPbI3 with substitution of the larger ions as high as 20-30%. These substituted hybrid organic inorganic perovskites retained similar optoelectronic properties. We discovered that the light-induced degradation in MAPbI3 and its substituted derivatives is autocatalytic, and we calculated rate coefficients for the degradation. All of the substituted hybrid organic inorganic perovskites showed light-induced degradation slower than that of MAPbI3, up to a 62% decrease in degradation rate coefficient, at all substitution percentages up to 20%. This work provides evidence that a high percentage of a variety of large ammonium cations can be substituted into the hybrid organic inorganic perovskite lattice without compromising its desirable optoelectronic properties. Insight into the autocatalytic mechanism of light-induced degradation wilI be valuable for designing additional strategies to improve the stability of hybrid organic inorganic perovskites. We also offer insights into how factors other than size, such as hydrogen bonding, influence the stability of the materials. Overall, we have shown that substitution of methylammonium ion for the much larger imidazolium, dimethylammonium, and guanidinium cations in MAPbI3 is a valid strategy for creating stable hybrid organic inorganic perovskite derivatives by slowing the rate of light -induced degradation.