Showing papers on "Heterojunction published in 2017"
TL;DR: In this article, a direct Z-scheme g-C3N4/SnS2 heterojunction was constructed by depositing SnS2 quantum dots onto the g-c3n4/snS2 surface in situ via a simple one-step hydrothermal method.
671 citations
TL;DR: There are a wide variety of processing routes that have been developed for 2D-hBN, including also those for doping, substitution, functionalization and combination with other materials to form heterostructures or h-BNC hybrid nanosheets, which are systematically elaborated for novel functions.
Abstract: Two dimensional hexagonal boron nitride (2D-hBN), an isomorph of graphene with a very similar layered structure, is uniquely featured by its exotic opto-electrical properties together with mechanical robustness, thermal stability, and chemical inertness. It is thus extensively studied for application in field effect transistors (FETs), tunneling devices, deep UV emitters and detectors, photoelectric devices, and nanofillers. 2D-hBN is considered as one of the most promising materials that can be integrated with other 2D materials, such as graphene and transition metal dichalcogenides (TMDCs), for the next generation microelectronic and other technologies. Although it is by itself an insulator, it can well be tuned by several strategies in terms of properties and functionalities, such as by doping, substitution, functionalization and hybridization, making 2D-hBN a truly versatile type of functional materials for a wide range of applications. In this review, the distinct structural characteristics of 2D-hBN, doping- and defect-induced variations in energy bands and structures, and resultant properties, are presented. There are a wide variety of processing routes that have been developed for 2D-hBN, including also those for doping, substitution, functionalization and combination with other materials to form heterostructures or h-BNC hybrid nanosheets, which are systematically elaborated for novel functions. The comprehensive overview provides the types of the state-of-the-art 2D-hBN made by new synthesis strategies, where the mainstream approaches include exfoliation, chemical vapor deposition, and gas phase epitaxy, together with several other new methods that have been successfully developed in the past few years. On the basis of the extraordinary electrical and functional properties and thermal–mechanical stability, the applications of hBN-based nanosheets as substrates and dielectrics, passivation layers, and nanofillers in nanodevices and nanocomposites are discussed, together with the peculiar optical and wetting characteristics.
643 citations
TL;DR: In this article, a self-powered solar-blind photodetector with a sharp cutoff wavelength at 266 nm was constructed by a simple one-step chemical vapor deposition method, and showed an ultrahigh responsivity (9.7 mA W−1) at 251 nm with a high UV/visible rejection ratio (R251 nm/R400 nm) of 6.9 × 102 under zero bias.
Abstract: Highly crystallized ZnO–Ga2O3 core–shell heterostructure microwire is synthesized by a simple one-step chemical vapor deposition method, and constructed into a self-powered solar-blind (200–280 nm) photodetector with a sharp cutoff wavelength at 266 nm. The device shows an ultrahigh responsivity (9.7 mA W−1) at 251 nm with a high UV/visible rejection ratio (R251 nm/R400 nm) of 6.9 × 102 under zero bias. The self-powered device has a fast response speed with rise time shorter than 100 µs and decay time of 900 µs, respectively. The ultrahigh responsivity, high UV/visible rejection ratio, and fast response speed make it highly suitable in practical self-powered solar-blind detection. Additinoally, this microstructure heterojunction design method would provide a new approach to realize the high-performance self-powered photodetectors.
576 citations
TL;DR: A periodic modulation of the local bandgap in the rotationally aligned MoS2/WSe2 bilayer creates a 2D electronic superlattice and quantitatively determine the influence of interlayer coupling on the electronic structure of the hetero-bilayer at different critical points.
Abstract: By using direct growth, we create a rotationally aligned MoS2/WSe2 hetero-bilayer as a designer van der Waals heterostructure. With rotational alignment, the lattice mismatch leads to a periodic variation of atomic registry between individual van der Waals layers, exhibiting a Moire pattern with a well-defined periodicity. By combining scanning tunneling microscopy/spectroscopy, transmission electron microscopy, and first-principles calculations, we investigate interlayer coupling as a function of atomic registry. We quantitatively determine the influence of interlayer coupling on the electronic structure of the hetero-bilayer at different critical points. We show that the direct gap semiconductor concept is retained in the bilayer although the valence and conduction band edges are located at different layers. We further show that the local bandgap is periodically modulated in the X-Y direction with an amplitude of ~0.15 eV, leading to the formation of a two-dimensional electronic superlattice.
443 citations
TL;DR: The photoactive contribution, up-conversion absorption, and nitrogen coordinating sites of g-C3 N4 NSs, highly dispersed vanadate nanocrystals, as well as the strong coupling and band alignment between them lead to superior visible-light-driven photoelectrochemical (PEC) and photocatalytic performance, competing with the best reported photocatalysis.
Abstract: 0D/2D heterojunctions, especially quantum dots (QDs)/nanosheets (NSs) have attracted significant attention for use of photoexcited electrons/holes due to their high charge mobility. Herein, unprecedent heterojunctions of vanadate (AgVO3 , BiVO4 , InVO4 and CuV2 O6 ) QDs/graphitic carbon nitride (g-C3 N4 ) NSs exhibiting multiple unique advances beyond traditional 0D/2D composites have been developed. The photoactive contribution, up-conversion absorption, and nitrogen coordinating sites of g-C3 N4 NSs, highly dispersed vanadate nanocrystals, as well as the strong coupling and band alignment between them lead to superior visible-light-driven photoelectrochemical (PEC) and photocatalytic performance, competing with the best reported photocatalysts. This work is expected to provide a new concept to construct multifunctional 0D/2D nanocomposites for a large variety of opto-electronic applications, not limited in photocatalysis.
395 citations
TL;DR: In this paper, a heterojunction interdigitated back contact solar cell with conversion efficiency of 26.6% was developed, which was independently confirmed by Fraunhofer Institute for Solar Energysystem Callab.
394 citations
TL;DR: This study designed and fabricated a stacking all-inorganic multilayer structure by using inorganic perovskite CsPbBr3 quantum dots (QDs) as the emissive layer and inorganic n- type MgZnO and p-type MgNiO as the carrier injectors, respectively, and obtained open possibilities for the design and development of high-efficiency and air-stable PeLEDs that are not dependent on expensive and less-stable organic
Abstract: Perovskite light-emitting diodes (PeLEDs), because of its fundamental scientific importance and practical applications in the fields of low-cost light source or display applications, have drawn worldwide attention in recent years. However, PeLEDs available today suffer from a compromise in their emission efficiency and operation stability. In this study, we designed and fabricated a stacking all-inorganic multilayer structure by using inorganic perovskite CsPbBr3 quantum dots (QDs) as the emissive layer and inorganic n-type MgZnO and p-type MgNiO as the carrier injectors, respectively. Through energy band engineering of carrier injectors by Mg incorporation and their thickness optimization, PeLEDs with maximum luminance of 3809 cd/m2, luminous efficiency of 2.25 cd/A, and external quantum efficiency of 2.39% have been realized, which are much better than most PeLEDs from CH3NH3PbBr3 films, and comparable with the highest results reported on CsPbBr3 QDs LEDs. More importantly, the unencapsulated PeLEDs in ...
370 citations
TL;DR: In this article, a novel atomic scale g-C3N4/Bi2WO6 heterojunction (UTCB) constructed by ultrathin g-CN and monolayer Bi2wO6 nanosheets (m-BWO) was successfully prepared by hydrothermal reaction.
Abstract: Although photocatalytic degradation is an ideal strategy for cleaning environmental pollution, it remains challenging to construct a highly efficient photocatalytic system by steering the charge flow in a precise manner. In this study, a novel atomic scale g-C3N4/Bi2WO6 heterojunction (UTCB) constructed by ultrathin g-C3N4 nanosheets (ug-CN) and monolayer Bi2WO6 nanosheets (m-BWO) was successfully prepared by hydrothermal reaction. The UTCB heterojunctions were characterized by various techniques including XRD, TEM, AFM, BET measurements, UV–vis spectrometry, and XPS. The results indicated that UTCB heterojunctions were assembly of m-BWO on ug-CN and presented high separation efficiency of photogenerated carriers. Under visible light irradiation, the optimum molar ratio of ug-CN/m-BWO (1:4, UTCB-25) reached almost 96.1% removal efficiency of IBF within 1 h, which was about 2.7 times as that of pure m-BWO. The photocatalytic mechanisms of UTCB-25 were revealed, suggesting that the synergistic effect of UTCB-25 heterojunction with strong interfacial interaction promoted the photoinduced charge separation. According to the LC–MS/MS, five photodegradation pathways of IBF under visible light irradiation were proposed. This study could open new opportunities for the rational design and a better understanding of atomic scale two dimensions/two dimensions (2D/2D) heterojunctions in environmental or other applications.
347 citations
TL;DR: In this paper, an oxygen defects-mediated Z-scheme mechanism was proposed for the charge separation in the heterojunction, which involved the recombining of photoinduced electrons that were trapped in the oxygen defects level of OD-ZnO directly with the holes in the valence band of g-C 3 N 4 at the interface.
Abstract: g-C 3 N 4 nanosheets were coupled with oxygen-defective ZnO nanorods (OD-ZnO) to form a heterojunction photocatalyst with a core-shell structure. Multiple optical and electrochemical analysis including electrochemical impedance spectroscopy, photocurrent response and steady/transient photoluminescence spectroscopy revealed that the g-C 3 N 4 /OD-ZnO heterojunction exhibited increased visible-light absorption, improved charge generation/separation efficiency as well as prolonged lifetime, leading to the enhanced photocatalytic activities for the degradation of 4-chlorophenol under visible-light illumination (λ > 420 nm). An oxygen defects-mediated Z-scheme mechanism was proposed for the charge separation in the heterojunction, which involved the recombining of photoinduced electrons that were trapped in the oxygen defects-level of OD-ZnO directly with the holes in the valence band of g-C 3 N 4 at the heterojunction interface. The detection of surface generated reactive species including O 2 − and OH clearly supported the Z-scheme mechanism. Moreover, the g-C 3 N 4 /OD-ZnO photocatalysts also exhibited enhanced visible-light Z-scheme H 2 evolution activity, with an optimal H 2 evolution rate of about 5 times than that of pure g -C 3 N 4 . The present work not only provided an alternative strategy for construction of novel visible-light-driven Z-scheme photocatalysts, but also gained some new insights into the role of oxygen-defects of semiconductors in mediating the Z-scheme charge separation.
320 citations
TL;DR: The key unknown parameters in MoSe2/WSe2 heterobilayers are determined by using rational device design and submicrometer angle-resolved photoemission spectroscopy (μ-ARPES) in combination with photoluminescence and the spectrum of a rotationally aligned heterobilayer reflects a mixture of commensurate and incommensurate domains.
Abstract: Combining monolayers of different two-dimensional semiconductors into heterostructures creates new phenomena and device possibilities. Understanding and exploiting these phenomena hinge on knowing the electronic structure and the properties of interlayer excitations. We determine the key unknown parameters in MoSe2/WSe2 heterobilayers by using rational device design and submicrometer angle-resolved photoemission spectroscopy (μ-ARPES) in combination with photoluminescence. We find that the bands in the K-point valleys are weakly hybridized, with a valence band offset of 300 meV, implying type II band alignment. We deduce that the binding energy of interlayer excitons is more than 200 meV, an order of magnitude higher than that in analogous GaAs structures. Hybridization strongly modifies the bands at Γ, but the valence band edge remains at the K points. We also find that the spectrum of a rotationally aligned heterobilayer reflects a mixture of commensurate and incommensurate domains. These results directly answer many outstanding questions about the electronic nature of MoSe2/WSe2 heterobilayers and demonstrate a practical approach for high spectral resolution in ARPES of device-scale structures.
317 citations
TL;DR: A simple methylamine solution-based additive is reported to improve film quality with nearly an order of magnitude reduction in intrinsic defect concentration, and an increase in carrier lifetime as a result of a decrease in shallow electronic disorder is observed.
Abstract: Minimization of defects in absorber materials is essential for hybrid perovskite solar cells, especially when constructing thick polycrystalline layers in a planar configuration. Here, a simple methylamine solution-based additive is reported to improve film quality with nearly an order of magnitude reduction in intrinsic defect concentration. In the resultant film, an increase in carrier lifetime as a result of a decrease in shallow electronic disorder is observed. This superior crystalline film quality is further evidenced via a doubled spin relaxation time as compared with other reports. Bearing sufficient carrier diffusion length, a thick absorber layer (≈650 nm) is implemented in planar devices to achieve a champion power conversion efficiency of 20.02% with a stabilized output efficiency of 19.01% under one sun illumination. This work demonstrates a simple approach to improve hybrid perovskite film quality by substantial reduction of intrinsic defects for wide applications in optoelectronics.
TL;DR: In this paper, a facile strategy for controllable synthesis of three-component Bi2O3/Bi2S3/MoS2 n-p heterojunction based on the formation of the intermediate Bi 2S3 by coupling Bi 2O3 and MoS2 was reported.
Abstract: As an important half reaction in solar-driven water splitting, it is still a challenging issue to develop low-cost and high efficient photocatalysts for water oxidation process. In this study, we reported a facile strategy for controllable synthesis of three-component Bi2O3/Bi2S3/MoS2 n-p heterojunction based on the formation of the intermediate Bi2S3 by coupling Bi2O3 and MoS2. The Bi2S3 was easily formed due to the strong interaction between Bi3+ and S2− ions with the assistance of the hydrothermal treatment. As a result, the prepared Bi2O3/Bi2S3/MoS2 nanocomposite exhibits enhanced ability of photocatalytic water oxidation (529.1 μmol h−1 g−1cat), which is 1.5 and 12.5 times higher than that of pure Bi2O3 and MoS2, respectively, under simulated solar light irradiation. Furthermore, the photoelectrochemical results reveal that the charge transportation feature and the donor density were apparently enhanced after the introduction of highly conductive layered MoS2, which indicates the enhancement of the photo-response and the improvement of charge separation efficiency.
TL;DR: It is revealed and demonstrated that a novel p-type conductor Cu(thiourea)I [Cu(Tu)I] incorporated in perovskite layer can effectively passivate the trap states of perovkite via interacting with the under-coordinated metal cations and halide anions at the perovSkite crystal surface.
Abstract: It is extremely significant to study the trap state passivation and minimize the trap states of perovskite to achieve high-performance perovskite solar cells (PSCs). Here, we have first revealed and demonstrated that a novel p-type conductor Cu(thiourea)I [Cu(Tu)I] incorporated in perovskite layer can effectively passivate the trap states of perovskite via interacting with the under-coordinated metal cations and halide anions at the perovskite crystal surface. The trap state energy level of perovskite can be shallowed from 0.35–0.45 eV to 0.25–0.35 eV. In addition, the incorporated Cu(Tu)I can participate in constructing the p–i bulk heterojunctions with perovskite, leading to an increase of the depletion width from 126 to 265 nm, which is advantageous for accelerating hole transport and reducing charge carrier recombination. For these two synergistic effects, Cu(Tu)I can play a much better role than that of the traditional p-type conductor CuI, probably due to its identical valence band maximum with that...
TL;DR: In this article, the authors demonstrate a feasible strategy of polymerizing the quantum-thick graphitic carbon nitride (g-C3N4) on to the surface of anatase titanium dioxide (TiO2) nanosheets with exposed {001} facets to form the TiO2@g-c 3N4 (TCN) core-shell quantum heterojunction for improving photocatalytic tetracycline degradation activity.
Abstract: Optimizing the heterojunction structure of semiconductor photocatalysts is significant for taking full advantage of their abilities for organic molecules degradation. Here, we demonstrate a feasible strategy of polymerizing the quantum-thick graphitic carbon nitride (g-C3N4) on to the surface of anatase titanium dioxide (TiO2) nanosheets with exposed {001} facets to form the TiO2@g-C3N4 (TCN) core-shell quantum heterojunction for improving photocatalytic tetracycline degradation activity. 100 mg of TCN photocatalyst shows the highest tetracycline degradation rate of 2.2 mg/min, which is 36% higher than that of the TiO2/g-C3N4 random mixture (TCN(mix)), 2 times higher than that of TiO2, and 2.3 times higher than that of bulk g-C3N4. Results also indicate that h+ and ·O2− are the main oxidant species for the efficient photocatalytic reaction. The decisive factors in improving the photocatalytic activity of TCN is the unique structural advantages of quantum-thick g-C3N4 shell, compact and uniform contact interface, richly available reaction sites, more surface adsorbed hydroxyl (OH) groups. Efficient electron transfer between TiO2 and g-C3N4 is also demonstrated by the significant enhancement of photocurrent response of TCN electrodes and decrement of fluorescence emission spectra. This work demonstrates new sights for synthesizing high-efficient and environment-stable photocatalysts by engineering the surface heterojunction.
TL;DR: In this paper, the authors used a bottom-up synthesis approach to fabricate 9- and 13-atom wide ribbons, enabling short-channel transistors with 105 on-off current ratio.
Abstract: Bottom-up synthesized graphene nanoribbons and graphene nanoribbon heterostructures have promising electronic properties for high-performance field-effect transistors and ultra-low power devices such as tunneling field-effect transistors. However, the short length and wide band gap of these graphene nanoribbons have prevented the fabrication of devices with the desired performance and switching behavior. Here, by fabricating short channel (L ch ~ 20 nm) devices with a thin, high-κ gate dielectric and a 9-atom wide (0.95 nm) armchair graphene nanoribbon as the channel material, we demonstrate field-effect transistors with high on-current (I on > 1 μA at V d = -1 V) and high I on /I off ~ 105 at room temperature. We find that the performance of these devices is limited by tunneling through the Schottky barrier at the contacts and we observe an increase in the transparency of the barrier by increasing the gate field near the contacts. Our results thus demonstrate successful fabrication of high-performance short-channel field-effect transistors with bottom-up synthesized armchair graphene nanoribbons.Graphene nanoribbons show promise for high-performance field-effect transistors, however they often suffer from short lengths and wide band gaps. Here, the authors use a bottom-up synthesis approach to fabricate 9- and 13-atom wide ribbons, enabling short-channel transistors with 105 on-off current ratio.
TL;DR: Air-stable doping of the n-type fullerene layer in an n-i-p planar heterojunction perovskite device is capable of enhancing device efficiency and improving device stability.
Abstract: Air-stable doping of the n-type fullerene layer in an n-i-p planar heterojunction perovskite device is capable of enhancing device efficiency and improving device stability. Employing a (HC(NH2 )2 )0.83 Cs0.17 Pb(I0.6 Br0.4 )3 perovskite as the photoactive layer, glass-glass laminated devices are reported, which sustain 80% of their "post burn-in" efficiency over 3400 h under full sun illumination in ambient conditions.
TL;DR: In this article, the authors demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p-n junctions in a MoSe2-WSe2 heterobilayer.
Abstract: Semiconductor heterostructures are backbones for solid-state-based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures have enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and a long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p–n junctions in a MoSe2–WSe2 heterobilayer. Applying a forward bias enables the first observation of electroluminescence from interlayer excitons. At zero bias, the p–n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the dir...
Journal Article•
TL;DR: A MoS2-graphene-WSe2 heterostructure for broadband photodetection in the visible to short-wavelength infrared range at room temperature that exhibits competitive device performance, including a specific detectivity of up to 10(11) Jones in the near-infrared region.
TL;DR: In this article, a modulation-doped two-dimensional electron gas (2DEG) at the β-(Al 0.2Ga 0.8)2O3/Ga2O 3 heterojunction by silicon delta doping was confirmed using capacitance voltage measurements.
Abstract: Modulation-doped heterostructures are a key enabler for realizing high mobility and better scaling properties for high performance transistors. We report the realization of a modulation-doped two-dimensional electron gas (2DEG) at the β-(Al0.2Ga0.8)2O3/Ga2O3 heterojunction by silicon delta doping. The formation of a 2DEG was confirmed using capacitance voltage measurements. A modulation-doped 2DEG channel was used to realize a modulation-doped field-effect transistor. The demonstration of modulation doping in the β-(Al0.2Ga0.8)2O3/Ga2O3 material system could enable heterojunction devices for high performance electronics.
TL;DR: In this article, a modulation-doped two-dimensional electron gas (2DEG) channel was used to realize a modulationdoped field effect transistor (FET) at the beta(Al 0.2Ga 0.8)2O3/ Ga2O 3 heterojunction using silicon delta doping.
Abstract: Modulation-doped heterostructures are a key enabler for realizing high mobility and better scaling properties for high performance transistors. We report the realization of modulation-doped two-dimensional electron gas (2DEG) at beta(Al0.2Ga0.8)2O3/ Ga2O3 heterojunction using silicon delta doping. The formation of a 2DEG was confirmed using capacitance voltage measurements. A modulation-doped 2DEG channel was used to realize a modulation-doped field-effect transistor. The demonstration of modulation doping in the beta-(Al0.2Ga0.8)2O3/ Ga2O3 material system could enable heterojunction devices for high performance electronics.
TL;DR: Li-doping of compact TiO2 can reduce the density of electron traps and increase the conductivity of the electron transport layer (ETL) of planar perovskite solar cells.
16 Jun 2017
TL;DR: In this paper, the theory and computation of excitons, plasmons and quasiparticles in 2D materials and their heterostructures are discussed, and a combined quantum/classical method is introduced and used throughout to account for dielectric screening and self-energy effects from substrates and van der Waals heterostructure including the difficult case of incommensurate lattices.
Abstract: Atomically thin two-dimensional (2D) materials host a rich set of excited states that differ substantially from those of their bulk counterparts due to quantum confinement and enhanced many-body effects. This Topical Review focuses on the theory and computation of excitons, plasmons and quasiparticles in 2D materials and their heterostructures. The general theory is illustrated by applications to various 2D materials including transition metal dichalcogenides, graphene, phosphorene, and hexagonal boron nitride. The weak and highly non-local dielectric function of atomically thin crystals is shown to be responsible for many of the unique properties exhibited by the 2D materials such as the formation of strongly bound, non-Hydrogenic excitons and the different signatures of excitons and plasmons in electron energy loss spectroscopy. Among other topics covered are spin-orbit coupling, trions, interlayer excitons, exciton dissociation, and substrate-induced band structure renormalisations. Technical issues associated with the application of the many-body GW method and Bethe-Salpeter equation to 2D materials are also discussed. A combined quantum/classical method is introduced and used throughout to account for dielectric screening and self-energy effects from substrates and van der Waals heterostructures including the difficult case of incommensurate lattices.
TL;DR: In this paper, the authors demonstrate the importance of the direct plasmonic coupling across the chemical interface for hot electron generation at a prototypical Ag nanocluster/TiO2 heterojunction by direct probing of the coherence and hot electron dynamics with two-photon photoemission spectroscopy.
Abstract: Integrating plasmonic nanoparticles with semiconductor substrates introduces strong optical resonances that extend and enhance the spectrum of photocatalytic and photovoltaic activity. The effect of plasmonic resonances has been variously attributed to the field nanoconfinement, plasmon–exciton coupling, hot electron transfer, and so on, based on action spectra of enhanced photoactivity. It remains unclear, however, whether energized carriers in the substrate are generated by the transfer of plasmonically generated hot electrons from the metal, as broadly believed, or directly by dephasing of the plasmonic field at the interface. Here, we demonstrate the importance of the direct plasmonic coupling across the chemical interface for hot electron generation at a prototypical Ag nanocluster/TiO2 heterojunction by direct probing of the coherence and hot electron dynamics with two-photon photoemission spectroscopy. Energy, time and material distributions of excitations in the Ag nanocluster/TiO2 heterojunction indicate that dielectric coupling with the substrate renormalizes the plasmon resonance of the Ag nanoparticle, and its dephasing directly generates hot electrons in TiO2 on a <10 fs timescale.
TL;DR: In this article, density functional theory (DFT) calculations were performed to investigate the structural, electronic, and optical properties of the layered C2N/MoS2 van der Waals (vdW) heterojunction.
Abstract: The nitrogenated porous two-dimensional (2D) material C2N has been successfully synthesized using a simple wet-chemical reaction, which provides a high-performance way to produce such 2D materials with novel electronic and optical properties. In this work, density functional theory (DFT) calculations were performed to investigate the structural, electronic, and optical properties of the layered C2N/MoS2 van der Waals (vdW) heterojunction. The C2N/MoS2 heterojunction was found to have a direct band gap of 1.30 eV and to present the typical type-II heterojunction feature, facilitating the effective separation of photogenerated electrons and holes. The calculated band alignment and enhanced optical absorption suggest that the C2N/MoS2 heterojunction should exhibit good light-harvesting properties. The vertical strain can effectively tune the electronic properties and optical absorption of the C2N/MoS2 heterojunction by changing the interaction between the pz orbital of C2N and the dz2 orbital of MoS2. The mo...
TL;DR: In this paper, a 2D-2D MnO2/g-C3N4 heterojunction composite was synthesized via a simple in-situ redox reaction between KMnO4 and MnSO4·H2O adsorbed on the surface of g-C 3N4 layers via CO bonding.
TL;DR: Low-bandgap CH3 NH3 (Pbx Sn1-x )I3 (0 ≤ x ≤ 1) hybrid perovskites demonstrating high surface coverage and superior optoelectronic properties are fabricated.
Abstract: Low-bandgap CH3 NH3 (Pbx Sn1-x )I3 (0 ≤ x ≤ 1) hybrid perovskites (e.g., ≈1.5-1.1 eV) demonstrating high surface coverage and superior optoelectronic properties are fabricated. State-of-the-art photovoltaic (PV) performance is reported with power conversion efficiencies approaching 10% in planar heterojunction architecture with small ( 100 cm2 V-1 s-1 ) intrinsic carrier mobilities.
TL;DR: Reduction of hysteresis by minimizing trap density via controlling thermal annealing time leads to the stabilized PCE of 18.84% from the normal planar structured FA0.9Cs0.1PbI3 PSK solar cell.
Abstract: Anomalous current–voltage (J–V) hysteresis in perovskite (PSK) solar cell is open to dispute, where hysteresis is argued to be due to electrode polarization, dipolar polarization, and/or native defects. However, a correlation between those factors and J–V hysteresis is hard to be directly evaluated because they usually coexist and are significantly varied depending on morphology and crystallinity of the PSK layer, selective contacts, and device architecture. In this study, without changing morphology and crystallinity of PSK layer in a planar heterojunction structure employing FA0.9Cs0.1PbI3, a correlation between J–V hysteresis and trap density is directly evaluated by means of thermally induced PbI2 regulating trap density. Increase in thermal annealing time at a given temperature of 150 °C induces growth of PbI2 on the PSK grain surface, which results in significant reduction of nonradiative recombination. Hysteresis index is reduced from 0.384 to 0.146 as the annealing time is increased from 5 to 100 ...
TL;DR: In this article, a two-step strategy of high temperature calcination and in situ photodeposition was used to synthesize WO 3 /g-C 3 N 4 /Ni(OH) x hybrids.
TL;DR: In this paper, the authors reported metallic NiPS3@NiOOH core-shell heterostructures as an efficient and durable electrocatalyst for the oxygen evolution reaction, exhibiting a low onset potential of 1.48 V and stable performance for over 160 h.
Abstract: We report metallic NiPS3@NiOOH core–shell heterostructures as an efficient and durable electrocatalyst for the oxygen evolution reaction, exhibiting a low onset potential of 1.48 V (vs RHE) and stable performance for over 160 h. The atomically thin NiPS3 nanosheets are obtained by exfoliation of bulk NiPS3 in the presence of an ionic surfactant. The OER mechanism was studied by a combination of SECM, in situ Raman spectroscopy, SEM, and XPS measurements, which enabled direct observation of the formation of a NiPS3@NiOOH core–shell heterostructure at the electrode interface. Hence, the active form of the catalyst is represented as NiPS3@NiOOH core–shell structure. Moreover, DFT calculations indicate an intrinsic metallic character of the NiPS3 nanosheets with densities of states (DOS) similar to the bulk material. The high OER activity of the NiPS3 nanosheets is attributed to a high density of accessible active metallic-edge and defect sites due to structural disorder, a unique NiPS3@NiOOH core–shell heter...
TL;DR: In this paper, a new kind of free-standing and flexible visible-light photocatalyst that can be easily recycled is developed for the first time, which is called the Cu/Cu 2 O/CuO heterojunction net.
Abstract: Facing the worldwide deepening water-shortage and water-contamination crises, developing visible-light photocatalysts for water purification is an urgent need. However, the present photocatalysts are mostly in form of powders and nanoparticles, which make the recovery inevitably depend on expansive separation processes. The great challenge of photocatalyst recovery severely limits their industry applications. Herein, a new kind of free-standing and flexible visible-light photocatalyst that can be easily recycled is developed for the first time. Cu/Cu 2 O/CuO heterojunction net is successfully fabricated by one-step calcination in air using low-cost Cu net as the matrix. The mixing narrow band gaps of the Cu/Cu 2 O/CuO heterojunction ensure its wide absorption band in visible region and effective electron/hole separation, and consequently lead to markedly photocatalytic activity under visible light irradiation. In addition, a large number of CuO nanowires growing on the heterojunction surface provide high specific surface area, expose abundant active sites for photocatalysis, and thus guarantee its high photocatalytic efficiency. More importantly, the Cu/Cu 2 O/CuO photocatalyst possesses flexible property for recovery, which is a significant advance in comparison with the previously reported photocatalysts. With a marvelous combination of low cost, facile fabrication, visible-light response, and easy recycling characteristic, this newly developed photocatalyst is expected to have great potential applications in water crises.