“…The spectra for the graphene ink is mostly featureless due to the linear dispersion of the Dirac electrons 38 , whereas the peak in the UV region is a signature of the Van Hove singularity in the graphene density of states 38 . The spectra for the h-BN ink shows a peak located at 218 nm, which corresponds to the interband transitions in the density of states 39 revealing an optical bandgap, E g of 5.69 eV (see ‘Methods’), which is consistent with previous reports determining the optical band gap for thin h-BN films 40 , 41 . Fig.…”
Fully printed wearable electronics based on two-dimensional (2D) material heterojunction structures also known as heterostructures, such as field-effect transistors, require robust and reproducible printed multi-layer stacks consisting of active channel, dielectric and conductive contact layers. Solution processing of graphite and other layered materials provides low-cost inks enabling printed electronic devices, for example by inkjet printing. However, the limited quality of the 2D-material inks, the complexity of the layered arrangement, and the lack of a dielectric 2D-material ink able to operate at room temperature, under strain and after several washing cycles has impeded the fabrication of electronic devices on textile with fully printed 2D heterostructures. Here we demonstrate fully inkjet-printed 2D-material active heterostructures with graphene and hexagonal-boron nitride (h-BN) inks, and use them to fabricate all inkjet-printed flexible and washable field-effect transistors on textile, reaching a field-effect mobility of ~91 cm2 V−1 s−1, at low voltage (<5 V). This enables fully inkjet-printed electronic circuits, such as reprogrammable volatile memory cells, complementary inverters and OR logic gates.
“…The spectra for the graphene ink is mostly featureless due to the linear dispersion of the Dirac electrons 38 , whereas the peak in the UV region is a signature of the Van Hove singularity in the graphene density of states 38 . The spectra for the h-BN ink shows a peak located at 218 nm, which corresponds to the interband transitions in the density of states 39 revealing an optical bandgap, E g of 5.69 eV (see ‘Methods’), which is consistent with previous reports determining the optical band gap for thin h-BN films 40 , 41 . Fig.…”
Fully printed wearable electronics based on two-dimensional (2D) material heterojunction structures also known as heterostructures, such as field-effect transistors, require robust and reproducible printed multi-layer stacks consisting of active channel, dielectric and conductive contact layers. Solution processing of graphite and other layered materials provides low-cost inks enabling printed electronic devices, for example by inkjet printing. However, the limited quality of the 2D-material inks, the complexity of the layered arrangement, and the lack of a dielectric 2D-material ink able to operate at room temperature, under strain and after several washing cycles has impeded the fabrication of electronic devices on textile with fully printed 2D heterostructures. Here we demonstrate fully inkjet-printed 2D-material active heterostructures with graphene and hexagonal-boron nitride (h-BN) inks, and use them to fabricate all inkjet-printed flexible and washable field-effect transistors on textile, reaching a field-effect mobility of ~91 cm2 V−1 s−1, at low voltage (<5 V). This enables fully inkjet-printed electronic circuits, such as reprogrammable volatile memory cells, complementary inverters and OR logic gates.
“…The lower intensities of non‐basal planes, that is, non (002) and (004) planes, signifies the alignment of BNNS in the horizontal plane as a result of their high aspect ratios. [ 42 ] The Raman spectrum of BNNS (Figure 2f) exhibited a peak similar to h‐BN as a result of the E 2g mode vibration. A slight upshift of the peak from 1364 to 1366 cm −1 is attributed to the weakened interlayer interactions in BNNS, corroborating the exfoliation of h‐BN into few‐layer nanosheets.…”
Electrically insulating polymer dielectrics with high energy densities and excellent thermal conductivities are showing tremendous potential for dielectric energy storage. However, the practical application of polymer dielectrics often requires mutually exclusive multifunctional properties such as high dielectric constants, high breakdown strengths, and high thermal conductivities. The rational assembly of 2D nanofillers of boron nitride nanosheets (BNNS) and reduced graphene oxide (rGO) into a wellaligned micro-sandwich structure in polyimide (PI) composites is reported. The alternating stacking of rGO and BNNS synergistically exploits the large difference in their electrical conductivities to yield a high dielectric constant with a moderate breakdown strength. Moreover, the distinctively separated rGO and BNNS layers give rise to higher thermal conductivities of composites than those containing mixed fillers because of reduced phonon scattering at the interfaces between two identical fillers, as verified by molecular dynamics simulations. Consequently, the micro-sandwich nanocomposite prevails over the PI film with a simultaneously high dielectric constant of ≈579, a high energy density (43-fold higher than PI) and an excellent thermal conductivity (11-fold higher than PI) at a low hybrid filler content of only 2.5 vol%. The multifunctional nanocomposites developed in this work are promising for flexible dielectrics with excellent heat dissipation.
“…The pyridinic C-N peaks are very low in the N1s spectra of Co/Co(OH) 2 @CP@BCN-2 and Co/Co(OH) 2 @CP@BCN-3 hybrids because of the excess of ZIF-67 emulsion ( Figure S9 , see SI ). It is well known fact that graphitic C-N and B-C species enhance the conductivity of BCN hybrid 40 41 42 43 . Furthermore, the contents of pyridinic (N-C) species in N-doped polyhedrons also increases at temperature above 800 °C, that enhance the electrochemical performance of the hybrid because of electroactive nature of pyridinic-N centers in carbon.…”
To cater for the demands of electrochemical energy storage system, the development of cost effective, durable and highly efficient electrode materials is desired. Here, a novel electrode material based on redox active β-Co(OH)2 and B, N co-doped graphene nanohybrid is presented for electrochemical supercapacitor by employing a facile metal-organic frameworks (MOFs) route through pyrolysis and hydrothermal treatment. The Co(OH)2 could be firmly stabilized by dual protection of N-doped carbon polyhedron (CP) and B/N co-doped graphene (BCN) nanosheets. Interestingly, the porous carbon and BCN nanosheets greatly improve the charge storage, wettability, and redox activity of electrodes. Thus the hybrid delivers specific capacitance of 1263 F g−1 at a current density of 1A g−1 with 90% capacitance retention over 5000 cycles. Furthermore, the new aqueous asymmetric supercapacitor (ASC) was also designed by using Co(OH)2@CP@BCN nanohybrid and BCN nanosheets as positive and negative electrodes respectively, which leads to high energy density of 20.25 Whkg−1. This device also exhibits excellent rate capability with energy density of 15.55 Whkg−1 at power density of 9331 Wkg−1 coupled long termed stability up to 6000 cycles.
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