Achieving dark current suppression and photocurrent enhancement simultaneously in 2D MoS₂ photodetector via Ag₇₀ nanocluster modification

Two-dimensional (2D) MoS₂ is considered an excellent candidate material for next-generation photodetectors. However, the high dark current and low photocurrent in MoS₂ devices severely hinder their practical application. Strategies for suppressing dark current and enhancing photocurrent should be explored. Herein, we propose a modification strategy for MoS₂ by utilizing Ag₇₀ nanoclusters (NCs) as electron reservoirs and photoabsorbers to suppress dark current and enhance the photocurrent of 2D MoS₂ photodetector. Remarkably, the dark current is effectively suppressed by four orders of magnitude, while the photocurrent is enhanced by over tenfold upon modification with Ag₇₀ NCs, compared to the pristine MoS₂ photodetector. The reduction in dark current is attributed to charge transfer from MoS₂ to Ag₇₀ NCs owing to the strong electron-withdrawing property of Ag₇₀ NCs. The increase in photocurrent benefits from enhanced optical absorption of the photodetector after Ag₇₀ NCs modification and the subsequent injection of photoexcited electrons from Ag₇₀ NCs to MoS₂. Compared to isolated MoS₂, the modulated photodetector shows exceptional improvements in several key figures of merit (such as responsivity, detectivity, external quantum efficiency, and photoswitching on/off ratio). This study opens up new avenues for building high-performance 2D MoS₂ photodetectors.