Prolonging exciton lifetime of WSe₂ monolayer through image dipole interaction leading to huge enhancement of photocurrent

Two-dimensional transition metal dichalcogenides (2D TMDs) have been demonstrated as one of the most outstanding materials not only for fundamental science but also for a wide range of photonic applications. However, an efficient way to control their excitonic properties is still needed for advanced applications with superior device performance. Here, we show that the exciton lifetime of WSe₂ monolayer can be prolonged using metamaterials. We observe a ∼100% reduction in the electron-hole recombination rate of WSe₂ monolayer placed on a hyperbolic metamaterial substrate and demonstrate that such a remarkable change results from the destructive image dipole interaction with the in-plane exciton transition dipole. Furthermore, this substantial increase in exciton lifetime leads to order-of-magnitude (10-fold) enhancement of photocurrent in the 2D WSe₂-based hybrid photodetector with metamaterials. Tailoring the optical transition properties of 2D TMD materials with specially designed metamaterials, demonstrated here, will pave the way for developing 2D material-based optoelectronics.