Spectral-selective high-efficient light absorption of large-area monolayer transition-metal dichalcogenides via critical coupling

Through the consideration of light trapping theory, a hybrid structure with silicon (Si) photonic crystal slabs and silica (SiO2) spacer layer on gold (Au) substrate has been proposed to enhance the light absorption of monolayer transition-metal dichalcogenides (TMDCs). Complete monolayer TMDCs is utilized without any demand of manufacture process to form periodic patterns, and multiple absorption peaks with near unity absorbance at visible wavelengths can be achieved. Further analysis indicates that the strong confinement of electromagnetic (EM) field through the principle of critical coupling gives rise to the high absorption. The method is a general way to realize the total absorption in any lossy atomically thin two-dimensional (2D) materials. This favorable field enhancement and tunability of absorption not only open up new approaches to accelerate the light-matter interaction in monolayer TMDCs, but also may be of great significance in wavelength-selective photoluminescence and photodetection.