Evolution of the Nature of Excitons and Electronic Couplings in Hybrid 2D Perovskites as a Function of Organic Cation π-Conjugation
Evolution of the Nature of Excitons and Electronic Couplings in Hybrid 2D Perovskites as a Function of Organic Cation π-Conjugation
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DOI：
10.1002/adfm.202108662
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发表时间：
2021-11-23
影响因子：
19
通讯作者：
Bredas, Jean-Luc
中科院分区：
文献类型：
--
作者：
Dai, Qingqing;Li, Hong;Bredas, Jean-Luc
二维钙钛矿由于其有机-无机杂化性质和层状结构而受到广泛关注。多量子阱结构通常形成，因为无机框架和有机间隔具有典型的良好分离的前沿能级。在这里，它集中在相反的图像，波函数杂化发生在两个组分的前沿轨道之间。这种杂化在调整无机层和有机层之间的电子耦合强度时出现。从理论上设计了一系列具有不同共轭度的二元有机隔振器模型。波函数杂化是在Dion-Jacobson二维钙钛矿中实现的，该钙钛矿结合了PbI4无机层和蒽-二（ethan-1-铵）有机间隔层。对电子能带结构的分析指出，有机和无机组分之间的电子耦合高达30-40 meV。这种耦合可以导致界面杂化激子的形成，或者导致有利于有机层中磷光的dexter型能量转移的出现。总的来说，研究结果表明，通过调整有机阳离子的共轭度以及有机和无机组分之间的结构接近度和电子耦合，可以观察到多种激子行为。
2D perovskites have attracted much attention, due to their organic-inorganic hybrid nature and layered configuration. Multi-quantum-well structures then generally form since the inorganic frameworks and organic spacers have typically well-separated frontier energy levels. Here, it is focused on the opposite picture where wavefunction hybridization occurs between the frontier orbitals of the two components. Such a hybridization emerges upon tuning the strength of electronic coupling between the inorganic and organic layers. A series of model diammonium organic spacers is theoretically designed with varying extent of pi-conjugation along their backbones. Wavefunction hybridization is realized in a Dion-Jacobson 2D perovskite combining PbI4 inorganic layers with anthracene-bis(ethan-1-ammonium) organic spacers. An analysis of the electronic band structures points to electronic couplings as high as 30-40 meV between the organic and inorganic components. Such couplings can lead to the formation of interfacial hybrid excitons or to the appearance of Dexter-type energy transfer conducive to phosphorescence in the organic layers. Overall, the results highlight that a variety of excitonic behaviors could be observed by tuning the degree of conjugation of the organic cations and the structural proximity and electronic couplings between the organic and inorganic constituents.