We investigate time-dependent diffusion mechanisms beyond two-dipole Forster resonance energy transfer (FRET). We demonstrate that the diffusion of excitons in thin films of quantum dots can be divided into two regimes depending on the excitation light intensity. Under a low-intensity regime, excited quantum dots do not interact with one another and a standard two-dipole FRET mechanism can be assumed as the source of a random walk process. As a result, there is a minimum amount of diffusion that will occur independently of the excitation power. In a high-intensity regime, a large number of quantum dots interact, inducing an energy transfer mechanism that surpasses two-dipole FRET in both range and rate. This process, which exhibits superradiance signatures, is temporary, occurring only when there is a large density of excitons present. Additionally, we utilize a phenomenon called oxidation hole burning (OHB) to pattern the lifetimes of excitons in quantum dot thin films laterally in an attempt to control diffusion rates and directionality.

中文翻译：

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具有空间图案化寿命的半导体量子点薄膜中的激发相关激子扩散


我们研究了双偶极福斯特共振能量转移 (FRET) 之外的时间依赖性扩散机制。我们证明，激子在量子点薄膜中的扩散可以根据激发光强度分为两种状态。在低强度状态下，受激量子点不会彼此相互作用，并且标准的双偶极子 FRET 机制可以被假定为随机游走过程的来源。因此，无论激发功率如何，都会发生最小量的扩散。在高强度状态下，大量量子点相互作用，产生在范围和速率上都超过双偶极 FRET 的能量转移机制。这个表现出超辐射特征的过程是暂时的，只有当存在大密度的激子时才会发生。此外，我们利用一种称为氧化烧孔（OHB）的现象来横向图案化量子点薄膜中激子的寿命，以试图控制扩散速率和方向性。