Zero-dimensional (0D) inorganic perovskites have attracted great interest for white-light-emitting applications because of their broad band emissions originating from self-trapped excitons. In this work, we explore and decipher exciton self-trapping in a series of 0D inorganic perovskites, A₄PbX₆ and A₄SnX₆ (A = K, Rb, and Cs; X = Cl, Br, and I) at the density functional theory level within the theoretical framework of the one-dimensional configuration coordinate diagram. We demonstrate that the formation of self-trapped states in A₄PbX₆ and A₄SnX₆ can be attributed to local structural distortions of individual [PbX₆]^4– and [SnX₆]^4– octahedra. Importantly, with the goal of both potentially improving the stability of the Sn derivatives and enhancing the emission efficiency, we further propose and design two types of 0D perovskite heterostructures, bulk A₄PbX₆/A₄SnX₆ mixtures and A₄PbX₆/A₄SnX₆ heterojunctions. We find that these 0D heterostructures exhibit type-I energy level alignment in which energy transfer from A₄PbX₆ to A₄SnX₆ is strongly promoted. Interestingly, these heterostructures show an increase in the transition dipole moments between the ground and self-trapped states compared to the pristine 0D perovskites. Our findings provide a new material design strategy for boosting self-trapped emissions with improved air stability for white-light-emitting applications.

中文翻译：

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促进零维钙钛矿异质结构中的自陷排放

零维（0D）无机钙钛矿因其自捕获的激子产生的宽带发射而引起了对发白光应用的极大兴趣。在这项工作中，我们探索和破译了一系列0D无机钙钛矿A ₄ PbX ₆和A ₄ SnX ₆（A = K，Rb和Cs； X = Cl，Br和I）中的激子自陷。密度泛函理论水平在理论框架内的一维配置坐标图。我们证明在A ₄ PbX ₆和A ₄ SnX ₆中自陷状态的形成可以归因于个体[PbX ₆] ^4–和[SnX ₆ ] ^4–八面体。重要的是，为了既有可能改善Sn衍生物的稳定性，又有提高发射效率的目的，我们进一步提出并设计了两种类型的0D钙钛矿异质结构，即本体A ₄ PbX ₆ / A ₄ SnX ₆混合物和A ₄ PbX ₆ /一个₄ SnX ₆异质结。我们发现这些0D异质结构表现出I型能级对齐，其中能量从A ₄ PbX ₆转移到A ₄ SnX ₆大力提拔。有趣的是，与原始0D钙钛矿相比，这些异质结构显示出基态和自陷态之间跃迁偶极矩的增加。我们的发现提供了一种新的材料设计策略，可提高自陷排放并改善白光发射应用的空气稳定性。