Exciton transport in most organic materials is based on an incoherent hopping process between neighboring molecules. This process is very slow, setting a limit to the performance of organic optoelectronic devices. In this Article, we overcome the incoherent exciton transport by strongly coupling localized singlet excitations in a tetracene crystal to confined light modes in an array of plasmonic nanoparticles. We image the transport of the resulting exciton–polaritons in Fourier space at various distances from the excitation to directly probe their propagation length as a function of the exciton to photon fraction. Exciton–polaritons with an exciton fraction of 50% show a propagation length of 4.4 μm, which is an increase by 2 orders of magnitude compared to the singlet exciton diffusion length. This remarkable increase has been qualitatively confirmed with both finite-difference time-domain simulations and atomistic multiscale molecular dynamics simulations. Furthermore, we observe that the propagation length is modified when the dipole moment of the exciton transition is either parallel or perpendicular to the cavity field, which opens a new avenue for controlling the anisotropy of the exciton flow in organic crystals. The enhanced exciton–polariton transport reported here may contribute to the development of organic devices with lower recombination losses and improved performance.

中文翻译：

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通过与等离子体纳米粒子阵列的强耦合控制有机晶体中的激子传播

大多数有机材料中的激子传输是基于相邻分子之间的非相干跳跃过程。这个过程非常缓慢，限制了有机光电器件的性能。在本文中，我们通过将并四苯晶体中的局部单重态激发与等离子体纳米粒子阵列中的受限光模式强耦合来克服非相干激子传输。我们对所得激子-极化子在距激发的不同距离处的傅里叶空间中的传输进行成像，以直接探测它们的传播长度作为激子与光子分数的函数。激子分数为 50% 的激子-极化子的传播长度为 4.4 μm，与单重态激子扩散长度相比增加了 2 个数量级。这种显着的增长已经通过有限差分时域模拟和原子多尺度分子动力学模拟得到了定性证实。此外，我们观察到当激子跃迁的偶极矩平行或垂直于腔场时，传播长度会发生变化，这为控制有机晶体中激子流的各向异性开辟了一条新途径。这里报道的增强的激子-极化子传输可能有助于开发具有较低复合损失和改进性能的有机器件。我们观察到，当激子跃迁的偶极矩平行或垂直于腔场时，传播长度会发生变化，这为控制有机晶体中激子流的各向异性开辟了一条新途径。这里报道的增强的激子-极化子传输可能有助于开发具有较低复合损失和改进性能的有机器件。我们观察到，当激子跃迁的偶极矩平行或垂直于腔场时，传播长度会发生变化，这为控制有机晶体中激子流的各向异性开辟了一条新途径。这里报道的增强的激子-极化子传输可能有助于开发具有较低复合损失和改进性能的有机器件。