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Exploiting intervalley scattering to harness hot carriers in IIIa??V solar cells
摘要： Hot carrier solar cells offer the potential to exceed the Shockley–Queisser limit. So far, however, there has been no clear route to achieve this result. Recently, the exploitation of the satellite valleys of the solar absorber material has been proposed as a feasible approach to harness hot carriers. Here, we show that, upon photoinduced and field-aided intervalley scattering to upper L-valleys, hot carriers can be harnessed in InGaAs/AlInAs heterojunctions at voltages defined by the upper valley (~1.25 V in the ideal case) rather than the bandgap of the InGaAs absorber (0.75 eV) under practical operational conditions. The efficiency of the present system does not exceed the single bandgap limit due to a mismatch in the valley degeneracy across the n+-AlInAs/n-InGaAs interface. However, we suggest that this is not a fundamental limitation to the realization of a hot carrier solar cell.
关键词： InGaAs/AlInAs heterojunctions,hot carrier solar cells,intervalley scattering,valley photovoltaic,Shockley–Queisser limit
更新于2025-09-23 15:19:57
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Selfa??Powered Flexible TiO <sub/>2</sub> Fibrous Photodetectors: Heterojunction with P3HT and Boosted Responsivity and Selectivity by Au Nanoparticles
摘要： A novel inorganic–organic heterojunction (TiO2/P3HT (poly(3-hexylthiophene)) is easily prepared by a combination of anodization and vacuumed dip-coating methods, and the constructed flexible fibrous photodetector (FPD) exhibits high-performance self-powered UV–visible broadband photoresponse with fast speed, high responsivity, and good stability, as well as highly stable performance at bending states, showing great potential for wearable electronic devices. Moreover, Au nanoparticles are deposited to further boost the responsivity and selectivity by regulating the sputtering intervals. The optimal Au/TiO2/P3HT FPD yields an ≈700% responsivity enhancement at 0 V under 350 nm illumination. The sharp cut-off edge and high UV–visible rejection ratio (≈17 times higher) indicate a self-powered flexible UV photodetector. This work provides an effective and versatile route to modulate the photoelectric performance of flexible electronic devices.
关键词： TiO2/P3HT heterojunctions,Au nanoparticles,fiber photodetectors,flexible devices,self-powered
更新于2025-09-23 15:19:57
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Controlling films structure by regulating 2D Ruddlesden-Popper perovskite formation enthalpy for efficient and stable tri-cation perovskite solar cells
摘要： The incorporation of bulky organic cations to metal-halide perovskites, forming the 2D-3D heterojunctions, has dramatically improved the stability of perovskite solar cells (PSCs). Nevertheless, the power conversion efficiencies (PCEs) of these PSCs are typically sacrificed because the formed 2D structures possess larger dielectric confinement, wider bandgaps, higher exciton binding energies and lower charge-carrier mobilities than the 3D perovskites. Here, we demonstrate that the environmental stability of the PSCs could be significantly improved without sacrificing the efficiency by introducing hydrophobic polyfluorinated cations (CF3CF2CH2NH3+, 5F-PA+) to the metal-halide perovskites. Due to the large 2D perovskite formation enthalpy with polyfluorinated cations, the addition of such cations will form a protective layer at the grain boundaries of 3D perovskite rather than form the 2D perovskites. The resultant solar cells based on 5F-PA0.05[Cs0.05(MA0.17FA0.83)0.95]0.95Pb(Br0.17I0.83)3 exhibit a substantially increased PCE of 22.86% compared with that (20.69%) of the control Cs0.05(MA0.17FA0.83)0.95Pb(Br0.17I0.83)3 devices. More importantly, the optimized devices could keep 80% of their original PCEs after >3000 h in ambient environment with 65 ± 10% relative humidity, which is attributed to hydrophobic fluorine moieties.
关键词： power conversion efficiency,perovskite solar cells,environmental stability,polyfluorinated cations,2D-3D heterojunctions
更新于2025-09-23 15:19:57
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Boosting the photocatalytic performances of covalent organic frameworks enabled by spatial modulation of plasmonic nanocrystals
摘要： Plasmonic Au nanocrystals (NCs) are incorporated into covalent organic frameworks (COFs) with precisely modulated distributions to improve the efficiency of electron-hole separation covalent reactions and assembly of NCs, sparsely dispersed Au NCs (AuSP/COFs) or the close packed ones (AuCP/COFs) in COFs are fabricated, in which the contributions of electron acceptors/cocatalysts on the catalytic properties of Au/COFs composites are addressed by EPR, PL, phenacyl bromide (conversion >99%, selectivity of acetophenone ~92.8%) under visible light irradiation, which are associated with accelerated electron transfer, increased available Au/COFs and optimize the charge-carrier utilization. Specifically, through balancing the rate of dynamic Schottky junctions and boosted interfacial reaction kinetics. Overall, this work contributes to the fundamental understanding of the how spatial distributions of NCs in COFs affect the photocatalytic performances.
关键词： metallic nanocrystals,heterojunctions,covalent organic frameworks,photocatalysis,inorganic/organic hybrids
更新于2025-09-23 15:19:57
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Novel Self-Powered Photodetector with Binary Photoswitching Based on SnS <sub/><i>x</i> </sub> /TiO <sub/>2</sub> Heterojunctions
摘要： Binary photoresponse characteristics can realize the optical signal processing and logic operations. The UV photodetectors (PDs) with SnSx nanoflakes and TiO2 nanorod arrays (NRs) show a novel binary photoswitching behavior (change in current from positive to negative) by manipulating the light wavelength without external power source, utilizing the interfacial recombination of the photogenerated carriers in the type-I SnSx/TiO2 heterojunctions. The enhanced responsivity (R*) and detectivity and fast photoresponse time for self-powered SnSx/TiO2 PDs can be achieved by adjusting the phase ratio of SnS and SnS2 nanoflakes. The binary photoswitching in the self-powered UV PDs can be applied in the encrypted optical signal processing and imaging in some special conditions without external bias.
关键词： self-powered photodetector,SnSx/TiO2,binary photoresponse,heterojunctions
更新于2025-09-23 15:19:57
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Highly Efficient Photoelectrochemical Water Splitting: Surface Modification of Cobalt-Phosphate-Loaded Co <sub/>3</sub> O <sub/>4</sub> /Fe <sub/>2</sub> O <sub/>3</sub> p-n Heterojunction Nanorod Arrays
摘要： Hematite (α-Fe2O3) as a photoanode material for photoelectrochemical (PEC) water splitting suffers from the two problems of poor charge separation and slow water oxidation kinetics. The construction of p–n junction nanostructures by coupling of highly stable Co3O4 in aqueous alkaline environment to Fe2O3 nanorod arrays with delicate energy band positions may be a challenging strategy for efficient PEC water oxidation. It is demonstrated that the designed p-Co3O4/n-Fe2O3 junction exhibits superior photocurrent density, fast water oxidation kinetics, and remarkable charge injection and bulk separation efficiency (ηinj and ηsep), attributing to the high catalytic behavior of Co3O4 for the oxygen evolution reaction as well as the induced interfacial electric field that facilitates separation and transportation of charge carriers. In addition, a cocatalyst of cobalt phosphate (Co-Pi) is introduced, which brings the PEC performance to a high level. The resultant Co-Pi/Co3O4/Ti:Fe2O3 photoanode shows a photocurrent density of 2.7 mA cm?2 at 1.23 VRHE (V vs reversible hydrogen electrode), 125% higher than that of the Ti:Fe2O3 photoanode. The optimized ηinj and ηsep of 91.6 and 23.0% at 1.23 VRHE are achieved on Co-Pi/Co3O4/Ti:Fe2O3, respectively, corresponding to the 70 and 43% improvements compared with those of Ti:Fe2O3. Furthermore, Co-Pi/Co3O4/Ti:Fe2O3 shows a low onset potential of 0.64 VRHE and long-time PEC stability.
关键词： photoanode,Co3O4,Fe2O3,p–n heterojunctions,Co-Pi
更新于2025-09-19 17:15:36
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AsP/InSe Van der Waals Tunneling Heterojunctions with Ultrahigh Reverse Rectification Ratio and High Photosensitivity
摘要： Van der Waals heterojunctions made of 2D materials offer competitive opportunities in designing and achieving multifunctional and high-performance electronic and optoelectronic devices. However, due to the significant reverse tunneling current in such thin p–n junctions, a low rectification ratio along with a large reverse current is often inevitable for the heterojunctions. Here, a vertically stacked van der Waals heterojunction (vdWH) tunneling device is reported consisting of black arsenic phosphorus (AsP) and indium selenide (InSe), which shows a record high reverse rectification ratio exceeding 107 along with an unusual ultralow forward current below picoampere and a high current on/off ratio over 108 simultaneously at room temperature under the proper band alignment design of both the Schottky junction and the heterojunction. Therefore, the vdWH tunneling device can function as an ultrasensitive photodetector with an ultrahigh light on/off ratio of 1 × 107, a comparable responsivity of around 1 A W?1, and a high detectivity over 1 × 1012 Jones in the visible wavelength range. Furthermore, the device exhibits a clear photovoltaic effect and shows a spectral detection capability up to 1550 nm. The work sheds light on developing future electronic and optoelectronic multifunctional devices based on the van der Waals integration of 2D materials with designed band alignment.
关键词： van der Waals heterojunctions,backward diodes,rectification,photodiodes,tunneling
更新于2025-09-19 17:15:36
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<i>In situ</i> synthesis of n–n Bi <sub/>2</sub> MoO <sub/>6</sub> & Bi <sub/>2</sub> S <sub/>3</sub> heterojunctions for highly efficient photocatalytic removal of Cr( <scp>vi</scp> )
摘要： Exploiting novel photocatalysts with high efficiency and durability for reduction of hexavalent chromium (Cr(VI)) has gained attention from fundamental science and industrial research. In this work, we synthesized novel two-dimensional (2D) n–n Bi2MoO6 & Bi2S3 heterojunctions by a facile in situ anion exchange process for remarkably efficient removal of Cr(VI). Results show that Bi2MoO6 & Bi2S3 heterojunctions with core–shell structures are formed through the intimate contact of Bi2MoO6 core and Bi2S3 shell. The prepared Bi2MoO6 & Bi2S3 heterojunctions exhibit unprecedented photocatalytic activity for reduction of Cr(VI) under visible light irradiation. The optimized BMO-S1 heterojunction displays the highest reduction efficiency (kapp = 0.164 min?1) for Cr(VI) reduction. To the best of our knowledge, it is one of the highest reduction rate achieved among reported photocatalysts for Cr(VI) reduction under visible-light irradiation. Detailed studies show that strong selective adsorption for Cr(VI) enhances this unprecedented photocatalytic activity. Moreover, the intimate heterojunction between Bi2MoO6 core and Bi2S3 shell can efficiently deteriorate the charge carrier recombination and Bi2S3 content can boost visible light harvesting, thereby contributing to the remarkable photocatalytic catalytic activity, which were proven by PL, EIS and transient photocurrent responses. Characterization of Mott–Schottky plots and DRS prove that the Bi2MoO6 & Bi2S3 heterojunctions established a type-II band alignment with intimate contact, accounting for the efficient transfer and separation of photogenerated carriers. This work provides a simple route for facial synthesis of heterojunction photocatalysts for Cr(VI) reduction in industrial applications.
关键词： photocatalytic,visible light,Cr(VI) reduction,heterojunctions,Bi2S3,core-shell structure,Bi2MoO6
更新于2025-09-19 17:15:36
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Upgrading the photocatalytic achievement of g-C3N4 nanosheets along decoration with Ag@TiO2 nanospheres for the preparation of vitamin B3
摘要： In this investigation, synthesis of ternary heterojunctions made of g-C3N4 sheets decorated with Ag@TiO2 nanospheres was successfully achieved. The reaction was initially started by combustion routine adopting silica of mesoporous type as a template to fabricate mesoporous C3N4 of graphite-like structure. After that, g-C3N4 nanosheets were decorated with TiO2 nanospheres and then TiO2 nanospheres were doped with Ag. Ag@TiO2/g-C3N4 ternary heterojunctions having 140 m2 g?1 specific surface area were produced. The resultant heterojunctions acquired a limited bandgap (2.26 eV) in addition to 3.4 nm pore size. The resultant Ag@TiO2/g-C3N4 nanocomposites were tested applying the photo-catalytic preparation of vitamin B3. It was observed that vitamin B3 could be synthesized adopting mesoporous Ag@TiO2/g-C3N4 ternary heterojunctions with a higher rate (33 times) than that when pristine TiO2 was adopted. The greater photo-catalytic action of the synthesized heterojunction might be correlated to the favorable Vis light absorption as well as the large separation between es and positive holes produced from inclusion of Ti3+ self-doping. In addition, huge amount of active sites was offered owing to the mesoporous network nature of the resultant heterojunctions. Finally, the dopant Ag nanoparticles positively supported the photocatalytic activity by its surface plasma resonance effect.
关键词： Ag@TiO2/g-C3N4 ternary heterojunctions,Vitamin B3,Visible photocatalyst
更新于2025-09-19 17:15:36
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Recent Progress of Heterojunction Ultraviolet Photodetectors: Materials, Integrations, and Applications
摘要： Ultraviolet photodetectors (UV PDs) with “5S” (high sensitivity, high signal-to-noise ratio, excellent spectrum selectivity, fast speed, and great stability) have been proposed as promising optoelectronics in recent years. To realize high-performance UV PDs, heterojunctions are created to form a built-in electrical field for suppressing recombination of photogenerated carriers and promoting collection efficiency. In this progress report, the fundamental components of heterojunctions including UV response semiconductors and other materials functionalized with unique effects are discussed. Then, strategies of building PDs with lattice-matched heterojunctions, van der Waals heterostructures, and other heterojunctions are summarized. Finally, several applications based on heterojunction/heterostructure UV PDs are discussed, compromising flexible photodetectors, logic gates, and image sensors. This work draws an outline of diverse materials as well as basic assembly methods applied in heterojunction/heterostructure UV PDs, which will help to bring about new possibilities and call for more efforts to unleash the potential of heterojunctions.
关键词： ultraviolet photodetectors,heterojunctions,semiconductors,van der Waals heterostructures,lattice-matched heterojunctions
更新于2025-09-19 17:13:59