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.

Atomically precise molecular-like metal nanoclusters (MNCs) exhibit unique properties, such as strong photoluminescence and absorption with inherent biocompatibility, which enable us to extend their applications to chemical sensing, biomedical imaging, optoelectronics, and many other areas. However, stimulated laser emission is greatly desirable to upgrade their more advanced functionalities. Here we provide a plausible approach to achieve this outstanding characteristic from MNCs. Quite interestingly, by integrating hyperbolic metamaterials (HMMs) with highly luminescent silver metal nanoclusters (Ag-TSA MNCs), a strong stimulated emission (random lasing action) with a low threshold of ∼0.5 kW cm −2 is discovered. The light emission is enhanced by ∼35 times when the solid-state assembly of Ag-TSA MNCs is integrated with HMM in comparison with that with a silicon substrate. The highk modes excited by the HMM offer the possibility of forming the coherent closed feedback loops necessary for random lasing actions, thereby decreasing the energy loss associated with the photons' propagation in the matrix. The simulations derived from the finite-difference time-domain method support the experimental results. Our study shown here makes an initial step to demonstrate stimulated laser action from metal nanoclusters. It is believed that there exist many other alternatives for exploring this emerging research topic for the future development of cost-effective and biocompatible optoelectronic devices.

Multilevel and flexible nonvolatile memory (NVM) is a promising candidate for data storage in next-generation devices but its high bias and low mobility of conducting channels are often its drawbacks. In this study, we demonstrate a low bias of smaller than 0.1 V and a high-mobility graphene layer as a conducting channel for flexible optoelectronic NVM based on a composite thin film of indium-based MOF-derived InCl 3 and 4,4-oxydiphthalic anhydride (odpta), Na[In 3 (odpt) 2 (OH) 2 (H 2 O) 2 ](H 2 O) 4 , and reduced graphene oxide (rGO). The optoelectronic NVM device can be encoded and erased optically by ultraviolet (UV) light and visible light, respectively. Our device also achieves memory states over 192 (6-bit storage) distinct levels, which can emerge as mass data storage. It also shows an excellent endurance of write−erase cycles under irradiation with a laser of varying wavelengths, the mechanical stability of more than 1000 bending cycles, and stable retention for longer than 10 000 s. These results open an alternative route for developing low bias and innovative optoelectronic technologies.