Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
Department of Chemistry, Colorado State University, Fort Collins, Colorado, 80523, USA.
Nat Commun. 2019 Mar 20;10(1):1276. doi: 10.1038/s41467-019-08980-x.
Two-dimensional perovskites have emerged as more intrinsically stable materials for solar cells. Chemical tuning of spacer organic cations has attracted great interest due to their additional functionalities. However, how the chemical nature of the organic cations affects the properties of two-dimensional perovskites and devices is rarely reported. Here we demonstrate that the selection of spacer cations (i.e., selective fluorination of phenethylammonium) affects the film properties of two-dimensional perovskites, leading to different device performance of two-dimensional perovskite solar cells (average n = 4). Structural analysis reveals that different packing arrangements and orientational disorder of the spacer cations result in orientational degeneracy and different formation energies, largely explaining the difference in film properties. This work provides key missing information on how spacer cations exert influence on desirable electronic properties and device performance of two-dimensional perovskites via the weak and cooperative interactions of these cations in the crystal lattice.
二维钙钛矿作为更具内在稳定性的太阳能电池材料而崭露头角。由于具有额外的功能，间隔有机阳离子的化学调谐引起了极大的关注。然而，有机阳离子的化学性质如何影响二维钙钛矿和器件的性质却很少有报道。在这里，我们证明了间隔阳离子的选择（即，对苯乙基铵的选择性氟化）会影响二维钙钛矿的薄膜性质，从而导致二维钙钛矿太阳能电池的不同器件性能（平均 n = 4）。结构分析表明，间隔阳离子的不同堆积排列和取向无序导致了取向简并和不同的形成能，这在很大程度上解释了薄膜性质的差异。这项工作提供了关键的缺失信息，说明间隔阳离子如何通过晶格中这些阳离子的弱协同相互作用，对二维钙钛矿的理想电子性质和器件性能施加影响。
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