Highly Efficient Photodetection in Metal Nanocluster/Graphene Heterojunctions

The molecule-like metal nanoclusters gained wide attention from biomedical to energy applications in recent years owing to their discrete spectra. These atomically precise metal nanoclusters exhibit a significant band opening and consequently the possibility for strong light emission. Based upon previous reports on conventional semiconductors, the semiconducting nature of these nanoclusters combined with two-dimensional semimetals can have a huge impact on optoelectronic devices. The present work demonstrates that a hybrid structure of glutathione stabilized gold nanoclusters (GSH-Au NCs) with monolayer graphene can serve as a highly sensitive photodetector. The underlying mechanism can be well understood by the fact that the photoexcited carriers in GSH-Au NCs enable them to effectively transfer into the highly conductive graphene transporting layer. Under 325 nm laser illumination, a photoresponsivity of 7 A W −1 estimated in GSH-Au NCs photodetector has been enhanced to 2 × 10 5 A W −1 through the hybrid GSH-Au NCs/graphene photodetector, which is the highest value among metal nanoclusters based devices. Additionally, the compatibility of metal nanocluster film on flexible substrates has been demonstrated. The GSH-Au NCs exhibit a stable photoresponse under the application of systematic mechanical strain, manifesting their excellent mechanical stability. Thus, our work establishes the outstanding photodetecting property of gold nanocluster thin films, which holds a promising potential for future development of cost-effective and solution-processed optoelectronic devices, including emerging wearable technology.