A-Site Management for Highly Crystalline Perovskites.,Advanced Materials

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A-Site Management for Highly Crystalline Perovskites.
Advanced Materials ( IF 27.4 ) Pub Date : 2019-11-11 , DOI: 10.1002/adma.201904702
Haonan Si ₁ , Zheng Zhang ₁ , Qingliang Liao ₁ , Guangjie Zhang ₁ , Yang Ou ₁ , Suicai Zhang ₁ , Hualin Wu ₁ , Jing Wu ₁ , Zhuo Kang ₁ , Yue Zhang _{1,

2}

Affiliation

An in-depth understanding and effective suppression of nonradiative recombination pathways in perovskites are crucial to their crystallization process, in which supersaturation discrepancies at different time scales between CH3 NH3 I (MAI, methylammonium iodide) and PbI2 remain a key issue. Here, an A-site management strategy via the introduction of an A-site placeholder cation, NH4 + , to offset the deficient MA+ precipitation by occupying the cavity of Pb-I framework, is proposed. The temporarily remaining NH4 + is substituted by subsequently precipitated MA+ . The temperature-dependent crystallization process with the generation and consumption of a transient phase is sufficiently demonstrated by the dynamic changes in crystal structure characteristic peaks through in situ grazing-incidence X-ray diffraction and the surface potential difference evolution through temperature-dependent Kelvin probe force microscopy. A highly crystalline perovskite is consequently acquired, indicated by the enlarged grain size, lowered nonradiative defect density, prolonged carrier lifetime, and fluorescence lifetime imaging. Most importantly, it is identified that the A-site IMA defect is responsible for such crystal quality optimization based on theoretical calculations, transient absorption, and deep-level transient spectroscopy. Furthermore, the universality of the proposed A-site management strategy is demonstrated with other mixed-cation perovskite systems, indicating that this methodology successfully provides guidance for synthesis route design of highly crystalline perovskites.

中文翻译：

高度结晶钙钛矿的现场管理。

钙钛矿中非辐射重组途径的深入理解和有效抑制对其结晶过程至关重要，在该过程中，CH3 NH3 I（MAI，甲基碘化碘）和PbI2在不同时间尺度上的过饱和差异仍然是关键问题。在此，提出了一种通过引入A-site占位阳离子NH4 +的A-site管理策略，以通过占据Pb-I框架的空洞来抵消MA +不足的沉淀。暂时残留的NH4 +被随后沉淀的MA +取代。通过原位掠入射X射线衍射产生的晶体结构特征峰的动态变化以及通过温度依赖的开尔文探针力演化出的表面电势差充分证明了随瞬态产生和消耗而随温度变化的结晶过程显微镜检查。因此获得了高度结晶的钙钛矿，其表现为增大的晶粒尺寸，降低的非辐射缺陷密度，延长的载流子寿命和荧光寿命成像。最重要的是，基于理论计算，瞬态吸收和深层瞬态光谱学，可以确定A位IMA缺陷是造成这种晶体质量优化的原因。此外，

更新日期：2020-01-27

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