Excitons, Coulomb-bound electron–hole pairs, are elementary photo-excitations in semiconductors that can couple to light through radiative relaxation. In contrast, dark excitons (X_D) show anti-parallel spin configuration with generally forbidden radiative emission. Because of their long lifetimes, these dark excitons are appealing candidates for quantum computing and optoelectronics. However, optical read-out and control of X_D states has remained challenging due to their decoupling from light. Here, we present a tip-enhanced nano-optical approach to induce, switch and programmably modulate the X_D emission at room temperature. Using a monolayer transition metal dichalcogenide (TMD) WSe₂ on a gold substrate, we demonstrate ~6 × 10⁵-fold enhancement in dark exciton photoluminescence quantum yield achieved through coupling of the antenna-tip to the dark exciton out-of-plane optical dipole moment, with a large Purcell factor of ≥2 × 10³ of the tip–sample nano-cavity. Our approach provides a facile way to harness excitonic properties in low-dimensional semiconductors offering new strategies for quantum optoelectronics.

中文翻译：

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纳米光学天线尖端珀塞尔效应对室温暗激子的辐射控制

激子是库仑束缚的电子-空穴对，是半导体中的基本光激发，可以通过辐射弛豫与光耦合。相反，深色激子（X _D）显示反平行自旋构型，通常禁止辐射发射。由于它们的使用寿命长，这些深色激子非常适合用于量子计算和光电技术。然而，由于X _D状态与光的解耦，因此光学读取和控制X _D状态仍然具有挑战性。在这里，我们提出了一种尖端增强的纳米光学方法，可以在室温下感应，切换和可编程地调制X _D发射。在金基底上使用单层过渡金属二硫化二氢（TMD）WSe ₂，我们证明了〜6 ×10通过天线尖端与暗激子平面外光学偶极矩的耦合，暗激子光致发光量子产率提高了⁵倍，尖端样品纳米腔的赛尔系数≥2×10 ³。我们的方法提供了一种在低维半导体中利用激子特性的简便方法，从而为量子光电子学提供了新的策略。