Anomalous circularly polarized light emission in organic light-emitting diodes caused by orbital-momentum locking
Anomalous circularly polarized light emission in organic light-emitting diodes caused by orbital-momentum locking
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DOI：
10.1038/s41566-022-01113-9
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发表时间：
2022-12-05
期刊：
影响因子：
35
通讯作者：
Yan, Binghai
中科院分区：
文献类型：
--
作者：
Wan, Li;Liu, Yizhou;Yan, Binghai
手性圆偏振（CP）光是许多光子技术的核心，从自旋信息的光通信到新颖的显示和成像技术。因此，在开发能够从有机发光二极管（OLED）发射强不对称CP光的手性发射材料方面已经做出了重大努力。已被广泛接受的是，活性层的分子手性决定了这种器件中CP发射的有利光手性，而与发光方向无关。在这里，我们发现，非常规地，相反传播的CP光表现出相反的手性，并且反转OLED中的电流流动也切换所发射的CP光的手性。这种方向相关的CP发射通过解决CP-0 LED中的既定问题将净偏振速率提高了几个数量级，其中由背电极反射的CP光通常会侵蚀测量的不对称性。通过详细的理论分析，我们将这种反常的CP发射归因于手性材料中普遍存在的拓扑电子性质，即轨道动量锁定。我们的工作为设计新的手征电子器件铺平了道路，并探索了手征材料、拓扑电子和CP光之间在量子领域的密切联系。
Chiral circularly polarized (CP) light is central to many photonic technologies, from the optical communication of spin information to novel display and imaging technologies. As such, there has been significant effort in the development of chiral emissive materials that enable the emission of strongly dissymmetric CP light from organic light-emitting diodes (OLEDs). It has been widely accepted that the molecular chirality of the active layer determines the favoured light handedness of the CP emission in such devices, regardless of the light-emitting direction. Here we discover that, unconventionally, oppositely propagating CP light exhibits opposite handedness, and reversing the current flow in OLEDs also switches the handedness of the emitted CP light. This direction-dependent CP emission boosts the net polarization rate by orders of magnitude by resolving an established issue in CP-OLEDs, where the CP light reflected by the back electrode typically erodes the measured dissymmetry. Through detailed theoretical analysis, we assign this anomalous CP emission to a ubiquitous topological electronic property in chiral materials, namely orbital-momentum locking. Our work paves the way to design new chiroptoelectronic devices and probes the close connections between chiral materials, topological electrons and CP light in the quantum regime.