Van der Waals (vdW) heterostructures with 2D materials have shown that atomically thin non‐volatile memories are advantageous in terms of integration, while offering high performance and excellent stability. The non‐volatile memory behavior of 2D materials has mainly been studied for single‐bit operation, and there is growing interest in expanding to multi‐bit operation to enhance the storage capacities of memory devices. However, the conditions or rules for generating the desired number of bits in 2D‐based multi‐bit memory remain to be identified. In this study, multiple bits are successfully created on non‐volatile memory based on vdW heterostructure floating‐gate memory (FGM) by systematically tuning the dimensions of the 2D materials. In particular, a fingerprint mechanism is established that links the bit number and dimensions of 2D crystals on vdW heterostructures. This approach could enable the precise generation of the desired number of bits in layered‐material‐based vdW FGMs.

In this work, a highly conductive organic cocrystal is investigated as an anode material for conducting agent-free lithium-ion battery (LIB) electrodes. A unique morphology of semiconducting fullerene (C 60 ) and contorted hexabenzocoronene (cHBC) is developed as a cocrystal that efficiently enhances the electron transfer during discharge and charge processes due to the formation of a well-defined junction between C 60 and cHBC. In particular, the present study reveals the exact cocrystal phase of orthorhombic Pnnm using grazing incidence X-ray diffraction characterization and computational methods. The detailed cocrystal structure analysis indicates that the columnar structure of C 60 /cHBC cocrystal facilitates the reliable vacant sites for Li + storage, which ultimately enhances the reversible capacity to 330 mAh g -1 at 0.1 A g -1 with long cyclability of 600 cycles in the absence of a conducting agent. Furthermore, the rate performance of the C 60 /cHBC cocrystal anode is improved compared to that of the graphite anode, indicating that the cocrystal formation between C 60 and cHBC enhances the charge transport at a high current density. It demonstrates that the approach of this study can be a promising strategy for preparing conducting agent-free organic cocrystal anodes, which also provides a viable design rule for high-performance LIBs electrodes.

Self-assembled alkane layers are introduced between graphene layers to physically block nanometer size defects in graphene and lateral gas pathways between graphene layers. A welldefined hexatriacontane (HTC) monolayer on graphene could cover nanometer-size defects because of the flexible nature and strong intermolecular van der Waals interactions of alkane, despite the roughness of graphene. In addition, HTC multilayers between graphene layers greatly improve their adhesion. This indicates that HTC multilayers between graphene layers can effectively block the lateral pathway between graphene layers by filling open space with close-packed self-assembled alkanes. By these mechanisms, alternately stacked composites of graphene and self-assembled alkane layers greatly increase the gas-barrier property to a water vapor transmission rate (WVTR) as low as 1.2 × 10 −3 g/(m 2 day), whereas stacked graphene layers generally show a WVTR < 0.5 g/ (m 2 day). Furthermore, the self-assembled alkane layers have superior crystallinity and wide bandgap, so they have little effect on the transmittance.