查看更多>>摘要：Thermoelectric(TE)generators capable of converting thermal energy into applicable electricity have gained great popularity among emerging energy conversion technologies.Biopolymer-based ionic thermoelectric(i-TE)materials are promising candidates for energy conversion systems because of their wide sources,innocuity,and low manufacturing cost.However,common physically crosslinked biopolymer gels induced by single hydrogen bonding or hydrophobic interaction suffer from low differential thermal voltage and poor thermodynamic stability.Here,we develop a novel i-TE gel with supramolecular structures through multiple noncovalent interactions between ionic liquids(ILs)and gelatin molecular chains.The thermopower and thermoelectric power factor of the ionic gels are as high as 2.83 mV K-1 and 18.33 μW m-1 K-2,respectively.The quasi-solid-state gelatin-[EMIM]DCA i-TE cells achieve ultrahigh 2 h output energy density(E2h=9.9 mJ m-2)under an optimal temperature range.Meanwhile,the remarkable stability of the supramolecular structure provides the i-TE hydrogels with a thermal stability of up to 80 ℃.It breaks the limitation that biopolymer-based i-TE gels can only be applied in the low temperature range and enables biopolymer-based i-TE materials to pursue better performance in a higher temperature range.
查看更多>>摘要：Hole transport material free carbon-based all-inorganic CsPbBr3 perovskite solar cells(PSCs)are promising for commercialization due to its low-cost,high open-circuit voltage(Voc)and superior stability.Due to the different solubility of PbBr2 and CsBr in conventional solvents,CsPbBr3 films are mainly obtained by multi-step spin-coating through the phase evolution from PbBr2 to CsPb2Br5 and then to CsPbBr3.The scalable fabrication of high-quality CsPbBr3 films has been rarely studied.Herein,an inkjet-printing method is developed to prepare high-quality CsPbBr3 films.The formation of long-range crystalline CsPb2Br5 phase can effectively improve phase purity and promote regular crystal stacking of CsPbBr3.Consequently,the inkjet-printed CsPbBr3 C-PSCs realized PCEs up to 9.09％,8.59％and 7.81％with active areas of 0.09,0.25,and 1 cm2,respectively,demonstrating the upscaling potential of our fabrication method and devices.This high performance is mainly ascribed to the high purity,strong crystal orientation,reduced surface roughness and lower trap states density of the as-printed CsPbBr3 films.This work provides insights into the relationship between the phase evolution mechanisms and crystal growth dynamics of cesium lead bromide halide films.
查看更多>>摘要：In designing efficient perovskite solar cells(PSCs),the selection of suitable electron transport layers(ETLs)is critical to the final device performance as they determine the driving force for selective charge extraction.SnO2 nanoparticles(NPs)based ETLs have been a popular choice for PSCs due to superior electron mobility,but their relatively deep-lying conduction band energy levels(ECB)result in substantial potential loss.Meanwhile,TiO2 NPs establish favorable band alignment owing to shallower ECB,but their low intrinsic mobility and abundant surface trap sites impede the final performance.For this reason,constructing a cascaded bilayer ETL is highly desirable for efficient PSCs,as it can rearrange energy levels and exploit on advantages of an individual ETL.In this study,we prepare SnO2 NPs and acetylacetone-modified TiO2(Acac-TiO2)NPs and implement them as bilayer SnO2/Acac-TiO2(BST)ETL,to assemble cascaded energy band structure.SnO2 contributes to rapid charge carrier transport from high electron mobility while Acac-TiO2 minimizes band-offset and effectively suppresses interfacial recombination.Accordingly,the optimized BST ETL generates synergistic influence and delivers power conversion efficiency(PCE)as high as 23.14％with open-circuit voltage(Voc)reaching 1.14 V.Furthermore,the BST ETL is transferred to a large scale and the corresponding mini module demonstrates peak performance of 18.39％PCE from 25 cm2 aperture area.Finally,the BST-based mini module exhibit excellent stability,maintaining 83.1％of its initial efficiency after 1000 h under simultaneous 1 Sun light-soaking and damp heat(85 ℃/RH 85％)environment.
查看更多>>摘要：Gravure printing is a promising large-scale fabrication method for flexible organic solar cells(FOSCs)because it is compatible with two-dimension patternable roll-to-roll fabrication.However,the unsuitable rheological property of ZnO nanoinks resulted in unevenness and looseness of the gravure-printed ZnO interfacial layer.Here we propose a strategy to manipulate the macroscopic and microscopic of the gravure-printed ZnO films through using mixed solvent and poly(vinylpyrrolidone)(PVP)additive.The regulation of drying speed effectively manipulates the droplets fusion and leveling process and eliminates the printing ribbing structure in the macroscopic morphology.The additive of PVP effectively regulates the rheological property and improves the microscopic compactness of the films.Following this method,large-area ZnO∶PVP films(28 × 9 cm2)with excellent uniformity,compactness,conductivity,and bending durability were fabricated.The power conversion efficiencies of FOSCs with gravure-printed AgNWs and ZnO∶PVP films reached 14.34％and 17.07％for the 1 cm2 PM6:Y6 and PM6∶L8-BO flexible devices.The efficiency of 17.07％is the highest value to date for the 1 cm2 FOSCs.The use of mixed solvent and PVP addition also significantly enlarged the printing window of ZnO ink,ensuring high-quality printed thin films with thicknesses varying from 30 to 100 nm.
查看更多>>摘要：Metal oxide charge transport materials are preferable for realizing long-term stable and potentially low-cost perovskite solar cells(PSCs).However,due to some technical difficulties(e.g.,intricate fabrication protocols,high-temperature heating process,incompatible solvents,etc.),it is still challenging to achieve efficient and reliable all-metal-oxide-based devices.Here,we developed efficient inverted PSCs(IPSCs)based on solution-processed nickel oxide(NiOx)and tin oxide(SnO2)nanoparticles,working as hole and electron transport materials respectively,enabling a fast and balanced charge transfer for photogenerated charge carriers.Through further understanding and optimizing the perovskite/metal oxide interfaces,we have realized an outstanding power conversion efficiency(PCE)of 23.5％(the bandgap of the perovskite is 1.62 eV),which is the highest efficiency among IPSCs based on all-metal-oxide charge transport materials.Thanks to these stable metal oxides and improved interface properties,ambient stability(retaining 95％of initial PCE after 1 month),thermal stability(retaining 80％of initial PCE after 2 weeks)and light stability(retaining 90％of initial PCE after 1000 hours aging)of resultant devices are enhanced significantly.In addition,owing to the low-temperature fabrication procedures of the entire device,we have obtained a PCE of over 21％for flexible IPSCs with enhanced operational stability.
查看更多>>摘要：To demonstrate flexible and tandem device applications,a low-temperature Cu2ZnSnSe4(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480 ℃ by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1％with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92％for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(～1.0 eV)so that the tandem cell yielded an efficiency of 20％.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.
查看更多>>摘要：For microelectronic devices,the on-chip microsupercapacitors with facile construction and high performance,are attracting researchers'prior consideration due to their high compatibility with modern microsystems.Herein,we proposed interchanging interdigital Au-/MnO2/polyethylene dioxythiophene stacked microsupercapacitor based on a microfabrication process followed by successive electrochemical deposition.The stacked configuration of two pseudocapacitive active microelectrodes meritoriously leads to an enhanced contact area between MnO2 and the conductive and electroactive layer of polyethylene dioxythiophene,hence providing excellent electron transport and diffusion pathways of electrolyte ions,resulting in increased pseudocapacitance of MnO2 and polyethylene dioxythiophene.The stacked quasi-solid-state microsupercapacitors delivered the maximum specific capacitance of 43 mF cm-2(211.9 F cm-3),an energy density of 3.8 μWh cm-2(at a voltage window of 0.8 V)and 5.1 μWh cm-2(at a voltage window of 1.0 V)with excellent rate capability(96.6％at 2 mA cm-2)and cycling performance of 85.3％retention of initial capacitance after 10 000 consecutive cycles at a current density of 5 mA cm-2,higher than those of ever reported polyethylene dioxythiophene and MnO2-based planar microsupercapacitors.Benefiting from the favorable morphology,bilayer microsupercapacitor is utilized as a flexible humidity sensor with a response/relaxation time superior to those of some commercially available integrated microsensors.This strategy will be of significance in developing high-performance on-chip integrated microsupercapacitors/microsensors at low cost and environment-friendly routes.
查看更多>>摘要：Nitrogen-doped three-dimensional graphene(N-doped 3D-graphene)is a graphene derivative with excellent adsorption capacity,large specific surface area,high porosity,and optoelectronic properties.Herein,N-doped 3D-graphene/Si heterojunctions were grown in situ directly on silicon(Si)substrates via plasma-assisted chemical vapor deposition(PACVD),which is promising for surface-enhanced Raman scattering(SERS)substrates candidates.Combined analyses of theoretical simulation,incorporating N atoms in 3D-graphene are beneficial to increase the electronic state density of the system and enhance the charge transfer between the substrate and the target molecules.The enhancement of the optical and electric fields benefits from the stronger light-matter interaction improved by the natural nano-resonator structure of N-doped 3D-graphene.The as-prepared SERS substrates based on N-doped 3D-graphene/Si heterojunctions achieve ultra-low detection for various molecules:10-8 M for methylene blue(MB)and 10-9 M for crystal violet(CRV)with rhodamine(R6G)of 10-10 M.In practical detected,10-8 M thiram was precisely detected in apple peel extract.The results indicate that N-doped 3D-graphene/Si heterojunctions based-SERS substrates have promising applications in low-concentration molecular detection and food safety.
查看更多>>摘要：Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm-2 as cathode and anode at 2 mA cm-2,and 79.5％and 80％capacity have been preserved at 50 mA cm-2.In the meantime,they all showed excellent cycling performance with negligible change after＞10 000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm-2 and 0.352 mW cm-3).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.
查看更多>>摘要：The orthorhombic CuNb2O6(O-CNO)is established as a competitive anode for lithium-ion capacitors(LICs)owing to its attractive compositional/structural merits.However,the high-temperature synthesis(＞900 ℃)and controversial charge-storage mechanism always limit its applications.Herein,we develop a low-temperature strategy to fabricate a nano-blocks-constructed hierarchical accordional O-CNO framework by employing multilayered Nb2CTx as the niobium source.The intrinsic stress-induced formation/transformation mechanism of the monoclinic CuNb2O6 to O-CNO is tentatively put forward.Furthermore,the integrated phase conversion and solid solution lithium-storage mechanism is reasonably unveiled with comprehensive in(ex)situ characterizations.Thanks to its unique structural merits and lithium-storage process,the resulted O-CNO anode is endowed with a large capacity of 150.3 mAh g-1 at 2.0 A g-1,along with long-duration cycling behaviors.Furthermore,the constructed O-CNO-based LICs exhibit a high energy(138.9 Wh kg-1)and power(4.0 kW kg-1)densities with a modest cycling stability(15.8％capacity degradation after 3000 consecutive cycles).More meaningfully,the in-depth insights into the formation and charge-storage process here can promote the extensive development of binary metal Nb-based oxides for advanced LICs.
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