Quasi-2D perovskite semiconductors can be created by introducing organic interlayer cations into 3D perovskites and possess large binding energy, superior stability, high luminance efficiency, and tunable bandgap, holding promising applications in blue-light emitting devices. Compared with mixed halide perovskites, quasi-2D bromide perovskites emit blue light with high color stability. However, multiple-phases usually co-exist in quasi-2D bromide perovskites, resulting in low color purity. In this work, three ammonium bromides, namely, 3-(trifluoromethyl)phenyltrimethylammonium bromide (F-PTABr), benzyltributylammonium bromide (BTBABr), and phenethylammonium bromide (PEABr), are employed to fabricate quasi-2D perovskite films with narrow phase distribution. PEA serves as the scaffold to stabilize the quasi-2D PEA₂Cs_n-1Pb_nBr_3n+1 perovskite structure and provides enough space to allow the F-PTA cation entering the interlayer, which further triggers the entrance of a larger BTBA cation into the interlayer. The large F-PTA and BTBA cations reduce the crystal size of the perovskite and narrow the phase distribution to n = 2. As a result, the photoluminescence spectrum of the PEA_0.9F-PTA_0.05BTBA_0.05-based perovskite film becomes unimodal and blue-shifts from 498 to 484 nm compared with the film using the PEA_1.0 cation. A sky-blue light-emitting diode with an external quantum efficiency of 0.6% is achieved using the PEA_0.9F-PTA_0.05BTBA_0.05-based perovskite as the emitter. We, therefore, demonstrate a strategy to prepare phase narrow quasi-2D perovskites with improved color purity by introducing ternary organic cations into the quasi-2D perovskites and envisage that promising device performance can be achieved with a further dedicated structure design of the ammonium cations.

中文翻译：

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使用三元有机阳离子制备天蓝色发光二极管的窄相位分布的准2D溴化钙钛矿纳米晶体

准2D钙钛矿半导体可以通过将有机层间阳离子引入3D钙钛矿中来制造，并具有大的结合能，出色的稳定性，高的发光效率和可调的带隙，在蓝光发射器件中拥有广阔的应用前景。与混合卤化物钙钛矿相比，准2D溴化物钙钛矿发出的蓝光具有较高的色彩稳定性。但是，多相通常共存于准2D溴化钙钛矿中，导致色纯度低。在这项工作中，使用三种溴化铵，即3-（三氟甲基）苯基三甲基溴化铵（F-PTABr），苄基三丁基溴化铵（BTBABr）和苯乙基溴化铵（PEABr），来制备具有窄相分布的准2D钙钛矿薄膜。PEA充当稳定准2D PEA ₂的支架Cs _n-1 Pb _n Br _{3n + 1}钙钛矿结构，并提供足够的空间以允许F-PTA阳离子进入中间层，这进一步触发了较大的BTBA阳离子进入中间层。大的F-PTA和BTBA阳离子减小钙钛矿的晶体尺寸并使相分布缩小到n =2。结果，基于PEA _0.9 F-PTA _0.05 BTBA _0.05的钙钛矿膜的光致发光光谱变为单峰和蓝色。与使用PEA _1.0阳离子的薄膜相比，α-离子从498 nm转变为484 nm 。使用PEA _0.9 F-PTA _0.05可获得外部量子效率为0.6％的天蓝色发光二极管BTBA _0.05基钙钛矿作为发射体。因此，我们展示了一种通过将三元有机阳离子引入准2D钙钛矿制备具有改善的色纯度的窄相准2D钙钛矿的策略，并设想通过铵阳离子的进一步专用结构设计可以实现有希望的器件性能。