Three-dimensional (3D) graphene networks are attracting ever-increasing attention in the field of energy storage because their unique architecture at macroscopic scales is beneficial for effective electron and ion transport. Herein, a novel interconnected 3D graphene mesh network (3D GMN) was successfully designed and fabricated by folded Ni meshes assisted chemical vapor deposition method. The structure parameters of 3D GMN can be controlled well by tuning the period of Ni mesh and the electroplating time. With the increase of the density of 3D GMN, the electrical conductivity of 3D GMN and the thermal conductivity of 3D GMN/epoxy composite are greatly improved compared to that of the 3D graphene foam. This 3D GMN enables the high capacity of 57 mA h g⁻¹ in an aluminum ion battery at the ultra-high rate of 40C with capacity retention of 96.5% after 200 cycles.

Synaptic devices with bipolar analog resistive switching behavior are the building blocks for memristor-based neuromorphic computing. In this work, a fully complementary metal-oxide semiconductor (CMOS)-compatible, forming-free, and non-filamentary memristive device (Pd/Al₂O₃/TaO_x/Ta) with bipolar analog switching behavior is reported as an artificial synapse for neuromorphic computing. Synaptic functions, including long-term potentiation/depression, paired-pulse facilitation (PPF), and spike-timing-dependent plasticity (STDP), are implemented based on this device; the switching energy is around 50 pJ per spike. Furthermore, for applications in artificial neural networks (ANN), determined target conductance states with little deviation (<1%) can be obtained with random initial states. However, the device shows non-linear conductance change characteristics, and a nearly linear conductance change behavior is obtained by optimizing the training scheme. Based on these results, the device is a promising emulator for biology synapses, which could be of great benefit to memristor-based neuromorphic computing.

Resistive switching devices based on binary transition metal oxides have been widely investigated. However, these devices invariably manifest threshold switching characteristics when the active metal electrode is silver, the dielectric layer is hafnium oxide and platinum is used as the bottom electrode, and have a relatively low compliance current (<100 μA). Here we developed a way to transform an Ag-based hafnium oxide selector into quantum-contact originated memory with a low compliance current, in which a graphene interface barrier layer is inserted between the silver electrode and hafnium oxide layer. Devices with structure Ag/HfO_x/Pt acts as a bipolar selector with a high selectivity of >10⁸ and sub-threshold swing of ∼1 mV dec⁻¹. After introducing a graphene interface barrier, high stress dependent (forming at +3 V) formation of localized conducting filaments embodies stable nonvolatile memory characteristics with low set/reset voltages (<±1.0 V), low reset power (6 μW) and multi-level potential. Grain boundaries of the graphene interface control the type of switching in the devices. A good barrier can switch the Ag-based volatile selector into Ag-based nonvolatile memory.

Large surface roughness, especially caused by the large particles generated during both the transfer and the doping processes of graphene grown by chemical vapor deposition (CVD) is always a critical issue that impedes the utility of graphene in the next-generation flexible thin-film opto-electronic devices such as organic light-emitting diodes (OLEDs), because it yields pinhole defects, leakage current, and electrical shorts, etc., causing non-emitting areas and device performance degradation over time. Here, an extremely smooth and robust PEDOT:PSS/graphene/PET hybrid anode is reported, prepared by direct and polymer-free transfer of CVD-grown graphene onto the smooth PET substrate. Flexible OLEDs with such hybrid anodes have the maximum brightness, current efficiency (CE) and power efficiency (PE), as high as 19 000 cd m⁻², 76 cd A⁻¹ and 61 lm W⁻¹, respectively, which are superior to those of the ITO/glass-based OLEDs. Moreover, a 2.5-inch monolithic flexible OLED has been successfully fabricated. The luminescence is very uniform and no dark spots are observed in the unencapsulated OLEDs, demonstrating the effectiveness of our strategies and the great prospect of graphene-based flexible OLEDs in the future foldable and rollable displays.