Real Device Applications Research Articles

Revival of Degraded CsPbI3 Nanocrystals by Diselenide Ligand and Nanocrystal Self-Assembly on Nanofibrilar Ligand Template.

Among the lead halide perovskite (LHP) family, CsPbI3 is known to be significantly vulnerable to moisture, which hinders its use in real device applications. It is reported that chalcogen-based ligands can better stabilize CsPbI3 and revive nanocrystals (NCs). Here, diphenyl diselenide (DPhDSe) ligand is used to revive the degraded CsPbI3 NCs through a post-synthetic treatment of adding a small amount of DPhDSe in the degraded NC dispersion. DPhDSe in the dispersion formed nanofibrillar crystals at a low temperature through the π-π stacking of the phenyl ring. The nanofibrils played as a template on which the NCs self-assembled and they are attached side-by-side to form microfibers. The microfiber powder containing the NCs is optically stable at ambient conditions and morphologically self-healable by mild thermal annealing due to the dynamic Se─Se bond. The mechanism of the structural changes, optical transitions, and chemical changes has been systematically characterized through electron microscopy, diffraction, spectroscopy, and elemental analysis.

Large-area ultrathin 2D Co(OH)2 nanosheets: a bifunctional electrode material for supercapacitor and water oxidation

Ultrathin film of active materials having thickness <5 nm emerged as a promising candidate for miniaturized energy storage and conversion devices. However, the small lateral size restricts its real device applications. Herein, we report large area, 2D, ultrathin (thickness: 4.3 ± 0.3 nm) Co(OH)2 nanosheets as bifunctional electrode material for supercapacitor and oxygen evolution reaction developed by ionic layer epitaxy method at the water-air interface. The symmetric supercapacitor device exhibited excellent volumetric capacitance of 2313 F/cm3 at 0.4 mA/cm2 current density. Additionally, it exhibited a remarkable volumetric energy density of 0.205 Wh/cm3 at a power density of 0.145 W/cm3, which is better than reported 2D electrode materials. Furthermore, the cobalt hydroxide (Co(OH)2) ultrathin-film electrodes showed improved oxygen evolution reaction electrocatalytic activity with low overpotential (ƞ10, 330 mV) and Tafel slope (47 mV/dec). The structural and morphological investigations after long-term operations show substantial stability of the electrode material. The theoretical investigations of electronic structures, quantum capacitance, and free energy profiles for the oxygen evolution reaction mechanism corroborate the experimental results.

Heavy elemental compound addition enhancing thermoelectric performance of Chromium Silicide synthesized by Spark plasma sintering

Silicide-based materials drive great potential in developing mid-temperature range thermoelectric generators (TEGs) applications. However, realizing the efficient and stable silicide materials is still a constraint for its real potential device applications. Chromium silicide will likely become p-type thermoelectric materials in this direction for thermoelectric power generation applications. However, high thermal conductivity values impede the figure-of-merit (zT). The present work adopts the chromium silicide, adding different weight percentages of well-known ZrCoSbSn compounds employing the compaction spark plasma sintering (SPS) technique. By adopting these combinations, the thermal conductivity is significantly reduced by enhanced scattering of heat-carrying phonons by multiple interfaces. Also, the maximum power factor value of ≃ 2.1 × 10−3 W/mK2 is achieved by employing a CrSi2 -ZrCoSbSn compound addition. The enhanced figure-of-merit value (zT) ≃ 0.26 is realized in the temperature at 623 K for the CrSi2-5wt% ZrCoSbSn compound material.

Reduced driving electric field of ionic salt doped nano-structured polymer dispersed liquid crystals device

The nano-structured polymer dispersed liquid crystal (NPDLC) possesses several intriguing properties due to its nano-confined structure and unprecedented flexibility. However, the involved polymer networks necessitate a higher operating field which deteriorates the device's feasibility for real-device applications. Here, we demonstrate a simple technique to reduce the driving field by introducing a small amount of ionic salt into the NPDLC. The selective occupation of ionic salt during the phase separation reduces the interfacial energy of LC molecules, dipping by 40 % (3.6 V/µm) of the driving electric field. The electrohydrodynamic instability created by localized ion transportation led to reduced LC anchoring strength at the polymer interface at which the operating field was reduced. Our design is versatile and a potential alternative to the present NPDLC.

Ordered FeCo2O4 & polypyrrole particles/branch nanotrees arrays grown on carbon fiber cloth substrate for energy storage applications

Supercapacitors are being utilized in energy storage devices with increasing interest a reason of their characteristics, which include high specific power, rapid charge and discharge rates, and long-term cycle stability. Most recently, research has concentrated on creating nanostructures to improve supercapacitors capacitance. The enhanced specific surface area of a material facilitates rapid diffusion of electrolyte ions; carbon fiber cloth (CFC) has been specifically utilized as a templates, leading to theoretical and practical advantages. In addition, the FeCo2O4 (FCO) and polypyrrole (PPy) to the CFC substrate is believed to be significant in enhancing the electrochemical behavior of supercapacitors. This study investigates the design approach of nanotree, configurations, and electrochemical characteristics of FCO-PPy on CFC for utilization in supercapacitors. The results of this research offer promising prospects for the advancement of future technologies to store energy. Porous FeCo2O4–polypyrrole (FCO-PPy) nanostructured arrays on CFC have been synthesis by a simple hydrothermal process with addition annealing process. The present research exhibits a unique nanostructure that exhibits exceptional electrochemical performance, characterized by a high capacitance and a desirable cycle life even under high rates of operation. The FCO-PPy nanowire arrays supported by CFC demonstrated a high specific capacitance of 1070 F g−1 at current densities of 2 A g−1 in a 2 M KOH aqueous solution when tested as an electrode in a system of supercapacitors. In addition, the FCO,CFC&PPy nanocomposite electrode shows excellent performance and long-term cyclic stability (90% capacitance retention after 10,000 cycles). The fabrication method presented here is cost-effective, facile, and scalable, which can open a new pathway for real device applications. Utilizing energy storage sustainability goods in business, adopting environmentally friendly chemicals, and being cost-conscious can considerably extend battery life. This includes breakthrough technology to mix modern materials, new electrode materials, new battery designs, and supercapacitors to revolutionize energy storage.

Enhancement and modulation of valley polarization in Janus CrSSe with internal and external electric fields.

The valley polarization, induced by the magnetic proximity effect, in monolayer transition metal dichalcogenides (TMDCs), has attracted significant attention due to the intriguing fundamental physics. However, the enhancement and modulation of valley polarization for real device applications is still a challenge. Here, using first-principles calculations we investigate the valley polarization properties of monolayer TMDCs CrS2 and CrSe2 and how to enhance the valley polarization by constructing Janus CrSSe (with an internal electric field) and modulate the polarization in CrSSe by applying external electric fields. Janus CrSSe exhibits inversion symmetry breaking, internal electric field, spin-orbit coupling, and compelling spin-valley coupling. A magnetic substrate of the MnO2 monolayer can induce a modest magnetic moment in CrSe2, CrSe2, and CrSSe. Notably, the Janus structure with an internal electric field has a much larger valley p compared with its non-Janus counterparts. Moreover, the strength of valley polarization can be further modulated by applying external electric fields. These findings suggest that Janus materials hold promise for designing and developing advanced valleytronic devices.

High Energy Density Porous RuO2 micro-Supercapacitors Using Protic Ionic Liquid Electrolytes

The rapid development of the Internet of Things (IoT) demands reliable and long-term energy supply to microelectronic devices distributed over the network with high power performance and less maintenance required.[1] Micro-supercapacitors (MSCs) have come to the foreground as miniaturized energy storage devices showing outstanding power density and long cycle life. However, the low cell voltage and low energy density remain major bottleneck that prevents their adoption in real device applications. To this end, several studies have been devoted to the engineering of MSC electrode materials and structural architecting of current collectors within the limited available footprint. This approach could offer opportunities to enhance the electrochemically active surface and mass loading of active materials with fast ion diffusion kinetics, leading to high areal energy density performance.[2] Although several efforts have been put forth in this direction, the complex synthesis route, unfavourable interfacial and mechanical stability of the electrode, electrolyte compatibility issues, etc. remain an arduous challenge.[3] The low cell voltage is another major issue preventing from achieving high energy density values in MSCs as it is directly linked to the electrochemical stability window (ESW) of the electrolytes used.[4] In addition, liquid-state electrolytes currently employed are inappropriate for the microfabrication route as it is prone to evaporation, leakage, and potential safety issues. Hence, a lot of research attention has been given to developing solid-state electrolytes able to afford large operational windows and help promote the application of on-chip MSCs. In this work, we have demonstrated the use of protic ionic liquid (PIL)-based electrolytes able to provide pseudocapacitance in hydrous ruthenium dioxide (RuO2) electrodeposited on interdigitated MSC substrates with extended operational cell voltage. As a pseudocapacitive material, RuO2 exhibits excellent conductivity, high electrochemical reversibility, and cycling stability.[5] On the other hand, as room temperature molten salts, PILs help to overcome evaporation and encapsulation problems associated with the conventional aqueous electrolytes and flammability and safety issues linked to common organic electrolytes.[6-9] We explored pyrrolidinium-based PILs with varying alkyl substitutions, their structure-property, and electrochemical studies for RuO2 MSCs. To further expand the use of these PILs in real devices, 3D MSCs with higher active material mass loading was realised using interdigitated porous Au current collector substrates. The PIL-based porous RuO2 MSCs showed superior charge storage and higher energy density performance as compared to conventional aqueous electrolytes. To envision the practical application of RuO2 MSCs and their subsequent integration with microelectronic devices, ionogel-based solid-state electrolytes were developed. This work opens pathways to develop micro-supercapacitors exhibiting high energy and power density by combining pseudocapacitive metal oxide-based active materials and protic ionic-liquid-based non-aqueous electrolytes and help their integration with on-chip IoT devices.

Enhancing optical characteristics of mediator-assisted wafer-scale MoS2 and WS2 on h-BN

Two-dimensional (2D) materials and their heterostructures exhibit intriguing optoelectronic properties; thus, they are good platforms for exploring fundamental research and further facilitating real device applications. The key is to preserve the high quality and intrinsic properties of 2D materials and their heterojunction interface even in production scale during the transfer and assembly process so as to apply in semiconductor manufacturing field. In this study, we successfully adopted a wet transfer existing method to separate mediator-assisted wafer-scale from SiO2/Si growing wafer for the first time with intermediate annealing to fabricate wafer-scale MoS2/h-BN and WS2/h-BN heterostructures on a SiO2/Si wafer. Interestingly, the high-quality wafer-scale 2D material heterostructure optical properties were enhanced and confirmed by Raman and photoluminescence spectroscopy. Our approach can be applied to other 2D materials and expedite mass production for industrial applications.

Atomistic Simulation of Temperature Dependent Magnetic Properties of Hole Doped 2H-VSe₂ Bilayer

Density functional theory calculations provide very accurate physical quantities at zero Kelvin. Nonetheless, it is necessary to understand how the physical quantities are changed at finite temperatures for real device application purposes. Here, we investigate the finite temperature dependent magnetic properties of hole doped 2H-VSe₂ bilayer structure using atomistic simulation. We find that the Curie temperature of 600 K at the hole concentration of 2.27×10SUP20/SUP cmSUP-3/SUP, and this is enhanced to 620 K at the hole concentration of 3.01×10SUP20/SUP cmSUP-3/SUP. We fit the temperature dependent magnetization curve (M(T)) using both Curie-Bloch and Kuz’min equations. We also calculate temperature dependent magnetic anisotropy energy. We find that the magnetic anisotropy energy is almost linearly decreased with increasing temperature. Besides, we obtain that the normalized temperature dependent anisotropy constant [K(T)/K(0)] shows the relation to the temperature dependent magnetization curve of [M(T)/M(0)] SUP2.9/SUP, and this is well converged with the exponent of 2.9 in the Callen-Callen theory.

Protic Ionic Liquid Electrolytes to Increase Areal Energy Density of RuO2 Micro-Supercapacitors

The rising growth of smart and autonomous microelectronic devices in the IoT (Internet of Things) era urges the development of advanced microscale energy sources with tailor-made features and customized energy/power requirements [1]. Micro-supercapacitors (MSCs) emerged as potential energy storage devices complementing micro-batteries to power ubiquitous sensor networks needed to foster the development of IoT. However, the low cell voltage and low energy density remain major bottleneck that prevents their application at a large scale in real devices. To mitigate this issue, several studies have been devoted to the engineering of MSC electrode materials and structural architecting of current collectors to enhance the surface area and areal energy density by considering the limited available footprint area [2]. This approach however has associated challenges such as complex synthesis route, the deleterious interfacial and mechanical stability of the electrode, and compatibility issues with the electrolyte and the current collector underneath [3]. Another important challenge to solve for reaching high energy density values in MSCs is the limited electrochemical stability window (ESW) of the electrolytes used as energy stored is directly related to the square of the cell voltage [4]. The electrolytes play a major role in deciding the ESW and liquid-state electrolytes currently employed are troublesome for the microfabrication process due to leakage, evaporation, and safety issues. Therefore, it’s imperative to develop alternative electrolytes including solid-state electrolytes reconcilable to the target application of MSCs. To address the low energy density challenge of current MSCs, we have developed interdigitated MSCs using hydrous ruthenium dioxide (RuO2) electrodes in combination with novel protic ionic liquid (PIL)-based electrolytes able to provide pseudocapacitance while affording a higher ESWs as compared to conventional aqueous electrolytes. As a state-of-the-art pseudocapacitive electrode material, RuO2 owns the key merits of excellent conductivity, high electrochemical reversibility, and cycling stability [5], whereas PILs could help alleviate issues facing currently used electrolytes such as evaporation and encapsulation problems pertaining to aqueous-based and flammability of common organic electrolytes [6], [7], [8]. In the next step, the slow proton transport kinetics of PILs were addressed by the doping of silicotungstic acid (SiWa, H4SiW12O40) with the PIL, which further boosted the pseudocapacitive current response with enlarged cell voltage. The real MSC device was realized by the use of RuO2 deposited on interdigitated porous Au current collectors having a high area enlargement factor (AEF) in combination with triethylammonium bis(trifluoromethanesulfonyl)imide (TEAH-TFSI)-based PIL. The resultant 3D MSC rendered a cell voltage exceeding 2V with areal capacitance as high as 86 mF cm-2 at 5 mV s-1 on par with the performance of 3D MSC tested using 0.5 M H2SO4 (cell voltage of 0.9 V and areal capacitance of 85 mF cm-2 at 5 mV s-1) but higher energy density performance (more than 4 times) using similar number of RuO2 deposition cycles. To demonstrate the potential integration in real on-chip device application, ionogel-based all-solid-state MSC is developed that showed performance comparable to liquid-state electrolyte with superior long-term cycling stability. This study gives a new perspective to develop all-solid-state micro-supercapacitors using pseudocapacitive active materials that can operate in ionic-liquid-based non-aqueous electrolytes compatible with on-chip IoT-based device applications seeking high areal energy/ power performance.

Operando photoelectron spectroscopy analysis of graphene field-effect transistors

In this study, operando photoelectron spectroscopy was used to characterize the performance of graphene field-effect transistors under working conditions. By sweeping the back-gate voltages, the carrier concentration of the graphene channel on the 150 nm Si3N4/Si substrate was tuned. From the C1s core level spectra acquired under the application of different gate voltages, the binding energy shifts caused by electric-field effects were obtained and analyzed. Together with the C1s peak shape information and the photoluminescence spectrum of the Si3N4/Si substrate, the presence of local potential across the x-ray beam spot associated with defects and gate leakage current in amorphous Si3N4 was identified. The presence of defects in Si3N4/Si substrate could not only screen the partial electric field generated by the back gate but also serve as long-range scattering centers to the carriers, thus affecting charge transport in the graphene channel. Our findings will help further investigate the dielectric/graphene interface properties and accelerate the utilization of graphene in real device applications.

Solution-Processed Red, Green, and Blue Quantum Rod Light-Emitting Diodes.

Solution-processed semiconductor nanocrystals are evolving as potential candidates for future display and lighting applications owing to their size-tunable emission, ultrasaturated colors, and compatibility with large-area flexible substrates. Among them, quantum rods (QRs) are emerging materials for optoelectronic applications, offering polarized emission, high light outcoupling efficiency, color purity, and better stability in solid films. However, synthesizing QRs covering the full visible wavelength region has been a big challenge, particularly in the blue range. Herein, we report for the first time the synthesis of red CdSe/CdS, green CdSe/ZnxCd1-xS/ZnS, and blue CdSe/ZnxCd1-xS/ZnS QRs and their application in red, green, and blue QR-based light-emitting diodes (QR-LEDs). We have improved the charge injection balance into the QRs through embedding a poly(methyl methacrylate) (PMMA) layer between the emissive and electron transport layers. The thin PMMA electron-blocking layer (EBL) suppresses the excessive electron flux and thus promotes charge injection balance and pushes the recombination zone back to the QR layer, resulting in 1.35×, 1.2×, and 1.7× peak external quantum efficiency improvement for red, green, and blue QR-LEDs, respectively. The efficiency roll-off of green and blue QR-LEDs with an EBL is less than 50% at maximum current density. The proposed red, green, and blue QR-LEDs open up an avenue toward further improving the light source efficiency and stability focusing on real device applications.

Temperature and time dependent electron trapping in Al2O3 thin films onto AlGaN/GaN heterostructures

In this article, the charge trapping phenomena in Al2O3 thin films grown by atomic layer deposition (ALD) on AlGaN/GaN heterostructures have been studied by time-dependent capacitance–voltage (C-V) measurements as a function of temperature. In particular, monitoring the transient of the capacitance enabled us to estimate the maximum depth of the insulating layer interested by the negative charge trapping effect under our bias stress conditions and to determine a charge traps density in the bulk Al2O3 in the order of 3 × 1019 cm−3. A temperature dependent C-V analysis up to 150 °C demonstrated the presence of two competitive mechanisms that rule the electron capture and emission in the Al2O3 film, characterized by activations energies of 22 and 88 meV respectively. Photoluminescence analyses revealed the presence of oxygen-related point defects in the insulator with a concentration in the order of ∼1020 cm−3 envisaging that only a fraction of them is electrically active. The results are useful to establish the thermal stability of the trapping phenomena, and the possible application in real devices.

Low defect and high electrical conductivity of graphene through plasma graphene healing treatment monitored with in situ optical emission spectroscopy

Fundamental studies on graphene (Gr) and its real device applications have been affected by unavoidable defects and impurities which are usually present in synthesized Gr. Therefore, post treatment methods on Gr have been an important subject of research followed by the community. Here, we demonstrate a post-treatment of cm-sized CVD-grown graphene in a Radio Frequency-generated low-pressure plasma of methane and hydrogen to remove oxygen functional groups and heal the structural defects. The optimum plasma treatment parameters, such as pressure, plasma power, and the ratio of the gases, are optimized using in-situ optical emission spectroscopy. This way we present an optimal healing condition monitored with in situ OES. A twofold increase in the conductivity of plasma-treated Gr samples was obtained. Plasma treatment conditions give insights into the possible underlying mechanisms, and the method presents an effective way to obtain improved Gr quality.

Biomass derived activated carbon based hybrid supercapacitors

Supercapacitors with prestigious electrochemical performance have achieved exceptional worth however, a facile environmentally friendly approach is still desired for electrode material with high charge storage capability. In this study, we have demonstrated the facile synthesis of activated carbon (AC) and strontium phosphate (Sr3(PO4)2) (sonochemical approach) ) for energy storage applications. The surface morphology and crystal structure of the synthesized materials are investigated via performing X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The electrochemical performance of synthesized material is carried out in three electrode assembly. The Sr3(PO4)2 reveals utmost specific capacity of 220 Cg−1 at 0.5 Ag−1 whereas, the AC delivers the high specific capacitance of 319.41 Fg−1 at 1 Ag−1 respectively. This synthesized materials are further employed in an hybrid architecture for real device application. The Sr3(PO4)2 is utilized as positive and AC as negative electrode. The fabricated device delivers excellent specific energy of 25.4 Whkg−1 at specific power of 425 Wkg−1. The maximum specific power 1870 Wkg−1 is also achieved along with specific energy of 14.5 Whkg−1. The device reveals the excellent capacity retention of 90 % after 3000 GCD series. Furthermore, the kinetics of charge storage mechanism is studied for the device by applying Dunn's model and the diffusive and capacitive contribution in overall device capacity is investigated. Moreover, the power law is utilized to confirm the hybrid nature of the device by calculating the b values. The projected approach result in electrode materials that have delivered potential energy storage performance.

Patterning Liquid Crystalline Organic Semiconductors via Inkjet Printing for High‐Performance Transistor Arrays and Circuits

AbstractLiquid crystalline (LC) organic semiconductors having long‐range‐ordered LC phases hold great application potential in organic field‐effect transistors (OFETs). However, to meet real device application requirements, it is a prerequisite to precisely pattern the LC film at desired positions. Here, a facile method that combines the technique of inkjet printing and melt processing to fabricate patterned LC film for achieving high‐performance organic integrated circuits is demonstrated. Inkjet printing controls the deposition locations of the LC materials, while the melt processing implements phase transition of the LC materials to form high‐quality LC films with large grain sizes. This approach enables to achieve patterned growth of high‐quality 2,7‐dioctyl[1]‐benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) LC films. The patterned C8‐BTBT LC film‐based 7 × 7 OFET array has 100% die yield and shows high average mobility of 6.31 cm2 V−1 s−1, along with maximum mobility up to 9.33 cm2 V−1 s−1. As a result, the inverters based on the patterned LC films reach a high gain up to 23.75 as well as an ultrahigh noise margin over 81.3%. Given the good generality of the patterning process and the high quality of the resulting films, the proposed method paves the way for high‐performance organic integrated devices.

GW band structure of monolayer MoS2 using the SternheimerGW method and effect of dielectric environment

Monolayers of transition-metal dichalcogenides (TMDs) hold great promise as future nanoelectronic and optoelectronic devices. An essential feature for achieving high device performance is the use of suitable supporting substrates, which can affect the electronic and optical properties of these two-dimensional (2D) materials. Here, we perform many-body GW calculations using the SternheimerGW method to investigate the quasiparticle band structure of monolayer ${\mathrm{MoS}}_{2}$ subject to an effective dielectric screening model, which is meant to approximately describe substrate polarization in real device applications. We show that, within this model, the dielectric screening has a sizable effect on the quasiparticle band gap; for example, the gap renormalization is as large as 250 meV for ${\mathrm{MoS}}_{2}$ with model screening corresponding to ${\mathrm{SiO}}_{2}$. Within the ${\mathrm{G}}_{0}{\mathrm{W}}_{0}$ approximation, we also find that the inclusion of the effective screening induces a direct band gap, in contrast to the unscreened monolayer. We also find that the dielectric screening induces an enhancement of the carrier effective masses by as much as 27% for holes, shifts plasmon satellites, and redistributes quasiparticle weight. Our results highlight the importance of the dielectric environment in the design of 2D TMD-based devices.

Unconventional dual-vacancies in nickel diselenide-graphene nanocomposite for high-efficiency oxygen evolution catalysis

Although nickel-based catalysts display good catalytic capability and excellent corrosion resistance under alkaline electrolytes for water splitting, it is still imperative to enhance their activity for real device applications. Herein, we decorated Ni0.85Se hollow nanospheres onto reduced graphene oxide (RGO) through a hydrothermal route, then annealed this composite at different temperatures (400 °C, NiSe2-400 and 450 °C, NiSe2-450) under argon atmosphere, yielding a kind of NiSe2/RGO composite catalysts. Positron annihilation spectra revealed two types of vacancies formed in this composite catalyst. We found that the NiSe2-400 catalyst with dual Ni-Se vacancies is able to catalyze the oxygen evolution reaction (OER) efficiently, needing a mere 241 mV overpotential at 10 mA·cm−2. In addition, this catalyst exhibits outstanding stability. Computational studies show favorable energy barrier on NiSe2-400, enabling moderate OH− adsorption and O2 desorption, which leads to the enhanced energetics for OER.

Strain distribution in wrinkled hBN films

Sapphire-supported hBN films of different thicknesses are grown using metalorganic vapour phase epitaxy technique by following a flow modulation scheme. Though these wafer-scale films are potential candidates for real device applications, they exhibit wrinkling. The wrinkles are a key signature of strain distribution in the films. We utilized Raman imaging to study the residual strain distribution in the wrinkled hBN films. An increase in the overall compressive strain in the films with an increase in the layer thickness is observed and explained. An empirical relation is proposed for estimating the wrinkle mediated strain relaxation from the morphology of the films. Furthermore, we show that the residual strain can be partially released by the delamination of the films.

Study of field emission properties of pure graphene-CNT heterostructures connected via seamless interface

Vertically aligned carbon nanotubes (CNTs) have proven to be one of the best materials for use as an efficient field emitter. To further improve their efficiency as well as long-term use in practical devices, it is necessary to reduce the quantum resistance originating from the interface between electrode and emitters and the entanglement of the CNTs in a bundle texture. Thus, the incorporation of graphene at the bottom of CNT bundles via a seamless carbonaceous interface can easily solve this bottleneck. In this work we have demonstrated for the first time, growth and field emission properties of pure seamless graphene-CNT heterostructures and pure seamless graphene-vertically patterned oriented CNTs heterostructures (SGVCNTs) on Si/SiO2 substrates in contrast to the bare CNT mats and few-layer graphene structures without using any tedious post transfer processes. It was observed that seamless SGVCNTs show better field emission performance in terms of higher current density (236 mA cm−2), lowered turn-on field (0.45 V μm−1) and threshold field (1.931 V μm−1 @100 mA cm−2), and improved field enhancement factor (β ∼ 41 315) which is improved ∼4 fold when compared to a bare CNT mat. The significant improvement of the field emission performance of SGVCNTs is mainly attributed to the low resistive seamless C–C covalent carbonaceous interface, the higher number of emitter sites and patterned vertical orientation that leads to long-term stability of the field emitter with minimal loss up to 32 h. This finding could provide an important solution for carbonaceous material based field emitters for real phase device applications.