Dimethylammonium Addition to Halide Perovskite Precursor Increases Vertical and Lateral Heterogeneity
Dimethylammonium Addition to Halide Perovskite Precursor Increases Vertical and Lateral Heterogeneity
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DOI：
10.1021/acsenergylett.1c02302
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发表时间：
2021-12
影响因子：
22
通讯作者：
S. Jariwala;Rishi E. Kumar;G. Eperon;Yangguang Shi;D. Fenning;D. Ginger
中科院分区：
文献类型：
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作者：
S. Jariwala;Rishi E. Kumar;G. Eperon;Yangguang Shi;D. Fenning;D. Ginger
向钙钛矿生长溶液中添加大的A位阳离子，如二甲基铵（DMA），已被证明可以提高卤化物钙钛矿太阳能电池的性能和长期操作稳定性。为了更好地理解这些改进的起源，我们探索了在以DMA0.1FA0.6Cs0.3Pb（I0.8Br0.2）3的比例向钙钛矿生长溶液中添加DMA之后甲脒（FA）、Cs、Pb和混合卤化物钙钛矿的膜结构、组成和光学性质的变化。使用飞行时间二次离子质谱（TOF-SIMS），我们表明DMA确实被掺入钙钛矿中，在表面具有更高的DMA浓度。使用光致发光（PL）显微镜和基于光诱导力显微镜（PiFM）的纳米红外（nanoIR）的组合，我们证明，将DMA到膜中导致局部带隙和集群的局部formamidinium（CH 5 N2+）组合物的局部异质性增加。此外，使用纳米X射线衍射，我们表明，DMA掺入也改变了局部结构组成，通过改变局部间距分布和晶粒尺寸。我们的研究结果表明，在A-网站的有机阳离子的组成变化驱动器的情况下观察到的DMA纳入薄膜的结构异质性。我们的研究结果还表明，虽然目前基于DMA添加剂的方法确实有利于操作稳定性和器件性能，但实现局部成分和结构均匀性的工艺优化可以进一步提高这两方面的性能，为使用DMA添加剂的太阳能电池带来进一步的收益。
Adding a large A-site cation, such as dimethylammonium (DMA), to the perovskite growth solution has been shown to improve the performance and long-term operational stability of halide perovskite solar cells. To better understand the origins of these improvements, we explore the changes in film structure, composition, and optical properties of a formamidinium (FA), Cs, Pb, and mixed halide perovskite following the addition of DMA to the perovskite growth solution in the ratio of DMA0.1FA0.6Cs0.3Pb(I0.8Br0.2)3. Using time-of-flight secondary-ion mass spectrometry (TOF-SIMS), we show that DMA is indeed incorporated into the perovskite, with a higher DMA concentration at the surface. Using a combination of photoluminescence (PL) microscopy and photoinduced force microscopy-based (PiFM) nanoinfrared (nanoIR), we demonstrate that incorporating DMA into the film leads to increased local heterogeneity in the local bandgap and clustering of the local formamidinium (CH5N2+) composition. In addition, using nano-X-ray diffraction, we demonstrate that DMA incorporation also alters the local structural composition by changing the locald-spacing distribution and grain size. Our results suggest that compositional variations in the organic cations at the A-site drive the structural heterogeneity observed in the case of DMA-incorporated films. Our results also suggest that while current DMA-additive-based approaches do have benefits to operational stability and device performance, process optimization to achieve local compositional and structural homogeneity could further boost both of these gains in performance, bringing further gains to solar cells using DMA additives.