Compositional engineering is a promising avenue for enhancing external quantum efficiency and adjusting emission wavelengths in halide perovskite light-emitting diodes (PeLEDs). However, the occurrence of ion migration within these materials poses a notable challenge as it can lead to elemental segregation during crystallization or under external stimuli such as heat, light, and bias, especially when simple mixing and alloying are employed. Such non-uniform distribution of elements detrimentally impacts color purity and long-term device stability in PeLEDs, highlighting the need to address elemental segregation issues. Additionally, quasi-2D perovskites have garnered attention for their potential to mitigate ion migration while maintaining superior optoelectronic properties attributable to the quantum confinement effect. Nevertheless, precise control over dimensionality remains challenging due to the thermodynamically favored 2D/3D phase separation, hindering efficient energy transfer. This review aims to provide an in-depth analysis of these phenomena. It explores the underlying mechanisms of elemental segregation and dimensionality separation, while summarizing recent efforts to overcome these challenges. Furthermore, the review discusses ongoing obstacles and suggests potential directions for future research in this evolving field.

中文翻译：

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卤化物钙钛矿发光二极管中的元素偏析和尺寸分离


成分工程是提高卤化物钙钛矿发光二极管 （PeLED） 中外部量子效率和调整发射波长的一种有前途的途径。然而，这些材料中离子迁移的发生构成了一个显著的挑战，因为它可能导致在结晶过程中或在热、光和偏压等外部刺激下发生元素偏析，尤其是在采用简单的混合和合金化时。这种元素的不均匀分布对 PeLED 中的颜色纯度和长期器件稳定性产生了不利影响，凸显了解决元素偏析问题的必要性。此外，准 2D 钙钛矿因其在减轻离子迁移同时保持归因于量子限制效应的卓越光电特性的潜力而受到关注。然而，由于热力学上有利于 2D/3D 相分离，因此对维度的精确控制仍然具有挑战性，阻碍了有效的能量转移。这篇综述旨在对这些现象进行深入分析。它探讨了元素分离和维度分离的潜在机制，同时总结了最近为克服这些挑战所做的努力。此外，本综述讨论了持续存在的障碍，并提出了这一不断发展的领域未来研究的潜在方向。