The spectral instability issue is a challenge in blue perovskite light-emitting diodes (PeLEDs). Dion–Jacobson (DJ) phase perovskites are promising alternatives to achieve high-quality blue PeLEDs. However, the current exploration of DJ phase perovskites is focused on symmetric divalent cations, and the corresponding efficiency of blue PeLEDs is still inferior to that of green and red ones. In this work, we report a new type of DJ phase CsPb(Br/Cl)₃ perovskite via introduction of an asymmetric molecular configuration as the organic spacer cation in perovskites. The primary and tertiary ammonium groups on the asymmetric cations bridge with the lead halide octahedra forming the DJ phase structures. Stable photoluminescence spectra were demonstrated in perovskite films owing to the suppressed halide segregation. Meanwhile, the radiative recombination efficiency of charges is improved significantly as a result of the confinement effects and passivation of charge traps. Finally, we achieved an external quantum efficiency of 2.65% in blue PeLEDs with stable spectra emission under applied bias voltages. To our best knowledge, this is the first report of asymmetric cations used in PeLEDs, which provides a facile solution to the halide segregation issue in PeLEDs.

中文翻译：

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基于非对称有机二胺的 Dion-Jacobson 钙钛矿的光谱稳定蓝光二极管

光谱不稳定性问题是蓝色钙钛矿发光二极管 (PeLED) 面临的挑战。Dion-Jacobson (DJ) 相钙钛矿是实现高质量蓝色 PeLED 的有希望的替代品。然而，目前DJ相钙钛矿的探索主要集中在对称二价阳离子上，蓝色PeLED的相应效率仍不如绿色和红色。在这项工作中，我们报告了一种新型 DJ 相 CsPb(Br/Cl) ₃钙钛矿通过引入不对称分子构型作为钙钛矿中的有机间隔阳离子。不对称阳离子上的伯和叔铵基团与卤化铅八面体桥接，形成 DJ 相结构。由于卤化物偏析受到抑制，钙钛矿薄膜显示出稳定的光致发光光谱。同时，由于约束效应和电荷陷阱的钝化，电荷的辐射复合效率显着提高。最后，我们在蓝色 PeLED 中实现了 2.65% 的外部量子效率，在施加的偏置电压下具有稳定的光谱发射。据我们所知，这是 PeLED 中使用的不对称阳离子的第一份报告，它为 PeLED 中的卤化物偏析问题提供了一种简便的解决方案。