基于碳灵敏度因子的社区P2P电能交易策略

为进一步提高用户侧分布式新能源的本地消纳,产消者间可开展点对点(P2P)交易并将交易电能的环境价值纳入收益来促进其低碳转型。以社区内的智能楼宇群为研究对象,提出基于碳灵敏度因子的P2P电能交易策略。通过对楼宇所交易的电能开展虚拟溯源分析确定电能不同的生产来源;建立碳灵敏度因子指标以量化不同来源电能的环境异质价值;依据提供或购买不同异质电能的贡献大小,设计非对称议价分配机制以激励低碳主体;采用自适应动态步长交替方向乘子法进行分布式求解以加快收敛速度。算例结果表明,所提电能交易策略可以有效提高分布式新能源的消纳率,降低各楼宇的用能成本,同时激励社区内部的绿色低碳转型。

Advances in designing heterojunction photocatalytic materials

Under the background of increasing energy crisis and global warming,semiconductor-based photocatalysis has received tremendous attention due to its potential application in green energy production,CO_(2) reduction and pollutant degradation.The photocatalytic activity of semiconductors,however,remains low due to issues like fast recombination of photo-generated electron-hole pairs,limited electron mobility,restricted optical absorption or insufficient active sites.Designing appropriate heterojunctions is proved to be a promising method to address most of these issues and thus to improve the photocatalytic performance.In this review,the working mechanism of various heterojunctions is presented systematically.The most recent advances of strategies in designing and preparing efficient heterojunction photocatalysts are further summarized and some perspectives on the future directions in this field are provided.

Influences of Low Energy Ion Implantation onProperties of Polyaniline/Si Heterojunction Solar Cells

Ion implantation may favorably modify the properties of polyaniline/Si heterojunction solar cells fabricated by the electrochemical method. Influences of the implantation on the absorption spectrum and the thermal stability were discussed and output properties were measured. The results show that the absorption spectrum of the polyaniline films modified by ion implantation is much wider; its pyrolytic temperature increases by 40℃, and the polyaniline/Si cell efficiency increases 18 and 3 times under the illumination of （10.92） and 37.2W/m2, respectively.

History of the Amorphous Silicon on Crystalline Silicon Heterojunction Solar Cell

Some commercially available solar panels with very high efficiencies for terrestrial photovoltaic applications are based on the amorphous silicon on crystalline silicon material system. This type ofheterostructure has more than 40 years＇ old history. The early development of the technology and the results, obtained in the last years with this type of solar cell are reviewed. In particular it is demonstrated why the physical understanding of the interface properties and band-structure was important for the development of high efficiency solar cells.

Study of organic solar cells with stacked bulk heterojunction structure

Organic solar cells with stacked bulk heterojutaction（BHJ） are investigated based on conjugated polymer. By using the solution spin-coating method, Poly[2-methoxy, 5-（2＇ -ethyl-hexyloxy） -1,4-phenylene vinylene] （MEH-PPV） and ZnO nanoparticles （50 nm） are mixed as the optical sense layer. Ag is used as inter-layer to connect the upper BHJ cell and the lower cell. The structures are ITO/PEDOT：PSS/MEH-PPV lAg / MEH-PPV：ZnO/Al. The open circuit voltage （Voc） of a stacked cell is about 3.7 times of that of an individual organic solar cell （ITO/PEDOT：PSS/MEH-PPV/Al）. The short circuit current （Jsc） of a stacked cell is increased by about 1.6 times of that of individual one.

Characteristics of Polyaniline/Si Heterojunction Solar Cell By Electrochemical Dye Sensitization

Using the electrochemical polymerization dye sensitization(ECDS) method, polyaniline(PAn), which is used as top region material in solar cells, is sensitized with direct blue dye(DS), and sensitized Al grid/DS-PAn/n-Si/Al heterojunction solar cells is prepared by ECDS. Influences of the ECDS on the absorption spectrum and the junction characteristics of the solar cell were discussed, and the output characteristics were measured. The results show that the absorption spectrum of the sensitized PAn films is much wider and stronger in Vis-range; the diode quality factor is about 6.3 and the height of latent barrier potential of p-n junction is 0.89eV; the short-circuit current and the conversion efficiency of sensitized DS-PAn/Si heterojunction solar cells are greatly improved, which the short-circuit current can increase 6 times, the fill factor is 57% and the efficiency can reach 1.42% under the illumination of 37.2W/m^2, respectively.

Study on Valence Band Offsets atStrained Heterojunctions

A method, which can predict the valence band offsets at strained layer heterojunctions under different strain situations only by calculating band structures and deformation parameters of the bulk materials, is suggested. The applicability of this method is verified by calculation of the valence band offsets at strained layer heterojuntions ,such as InP/InAs, InP/GaP, GaAs/InAs, GaP/GaAs and AlAs/InAs with various strain conditions.

Selectively constructing sandwich-like heterostructure of CdS/PbTiO_(3)/TiO_(2)to improve visible-light photocatalytic H_(2)evolution

Fast migration and efficient spatial separation of photogenerated charges in photocatalytic materials are indispensable to efficient solar water splitting reactions.Here,we construct a three-phase heterostructure of CdS/PbTiO_(3)/TiO_(2)by selectively depositing CdS and TiO_(2)at oppositely poled crystal facets of PbTiO_(3)using single-domain ferroelectric PbTiO_(3).The heterostructure has matching band edge alignments and strong interfacial connections at different moieties.The heterostructure combines the interfacial electrical and ferroelectric fields because of their peculiar microstructures,which provide a strong driving force throughout the whole bulk to separate photogenerated charges.Almost two orders of magnitude improvement of visible-light-driven photocatalytic H_(2) production has been realized in CdS/PbTiO_(3)/TiO_(2)compared with bare PbTiO_(3)/TiO_(2),showing the efficiency of charge separation in the heterostructure.The idea of combining ferroelectrics with potential light capture semiconductor provides a paradigm to accurately design charge migration pathways,bringing a step closer to efficient solar water splitting.

Surface plasmonic effect and scattering effect of Au nanorods on the performance of polymer bulk heterojunction solar cells

The surface plasmonic effect and scattering effect of gold nanorods(AuNRs) on the performance of bulk heterojunction photovoltaic devices based on the blend of polythiophene and fullerene are investigated.AuNRs enhance the excitation since the plasmonic effect increases the electric field,mainly in the area near the interface between the active layer and AuNRs.The results show that the incident photo-to-electron conversion efficiency(IPCE) obviously increases for the device with a layer of gold nanorods,resulting from the plasmonic effect of AuNRs in the range of 500-670 nm and the scattering effect in the range of 370-410 nm.The power conversion efficiency(PCE) is increased by 7.6% due to the near field effect of the localized surface plasmons(LSP) of AuNRs and the scattering effect.The short circuit current density is also increased by 9.1% owing to the introduction of AuNRs.However,AuNRs can cause a little deterioration in open circuit voltage.

Single step fabrication of N-doped graphene/Si3N4/SiC heterostructures

In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. The ability to dope graphene with electron-donor nitrogen heteroatoms is highly important for modulating electrical properties of graphene. Here we demonstrate a transfer-free method to directly grow large area quasi free-standing N-doped graphene bilayers on an insulating substrate （Si3N4）. Electron-bombardment heating under nitrogen flux results in simultaneous growth of N-doped graphene and a Si3N4 layer on the SiC surface. The decoupling of N-doped graphene from the substrate and the presence of Si3N4 are identified by X-ray photoemission spectroscopy and low-energy electron diffraction. The substitution of nitrogen atoms in the graphene planes was confirmed using high resolution X-ray photoemission spectroscopy which reveals several atomic configurations for the nitrogen atoms： Graphitic-like, pyridine-like, and pyrrolic- like. Furthermore, we demonstrated for the first time that N-doped graphene could be used to efficiently probe oxygen molecules via nitrogen atom defects.

Two-dimensional like conjugated copolymers for high efficiency bulk-heterojunction solar cell application:Band gap and energy level engineering

Three two-dimensional like conjugated copolymers PFSDCN,PFSDTA and PFSDCNIO,which consist of alternating fluorene and triphenylamine main chain,and different pendant acceptor groups (malononitrile,1,3-diethtyl-2-thiobarbituric acid and 2-(1,2-dihydro-1-oxoinden-3-ylidene)malononitrile) with thiophene as π-bridge,have been designed,synthesized and characterized.The structure-property relationships of the two-dimensional like conjugated copolymers were systematically investigated.The absorption spectra,band gaps,and energy levels of the polymers were effectively tuned by simply attaching different acceptor groups.As the electron-withdrawing ability of the acceptors increased,the band gaps of the polymers were narrowed from 2.05 to 1.61 eV;meanwhile,the LUMO energy levels of the polymers decreased from -3.27 to -3.75 eV,whereas their relatively deep HOMO energy levels of ～-5.35 eV were preserved.BHJ solar cells were fabricated and characterized by using the three polymers as donor materials and the highest power conversion efficiency of 2.87% was achieved for the device based on PFSDTA:(6,6)-phenyl-C71-butyric acid methyl ester blend.

Optimization and degradation of rubrene/C_(70) heterojunction solar cells

Small molecule organic solar cells （OSCs） with the structure of indium tin oxide （1TO）/molybdenum trioxide （MOO3） （5 nm）/rubrene （x nm）/fullerene （C70） （y nm）/2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline （BCP） （6 nm）/aluminum （A1） （150 nm） are fabricated. The thickness of active layer for the devices is investigated in details. The results show that the optimum thicknesses of rubrene layer and C70 layer are 30 nm and 25 nm, respectively. The degradation of the device is also investigated. The result indicates that the open-circuit voltage （Voo） does not change, while the short-circuit current density （Jsc）, fill factor （FF） and power conversion efficiency （PCE） decrease continuously with time. The degradation can be attributed to the oxygen in ambient diffusing and infiltrating into the active materials and reacting with C70 in cells, which can result in the increase of interfacial series resistance.

Two-dimensional SnO_2/graphene heterostructures for highly reversible electrochemical lithium storage

The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimensional (2D)nanomaterials and their heterostructures are an intense area of study and promise great potential in electrochemical lithium storage owing to their unique properties that result from structural planar confinement.Here we report a microwave chemistry strategy to integrate ultrathin SnO2 nanosheets into graphene layer to construct surface-to-surface 2D heterostructured architectures,which can provide unique structural planar confinement for highly reversible electrochemical lithium storage.The as-synthesized 2D SnO2/graphene heterostructures can exhibit high reversible capacity of 688.5mAh g^-1 over 500cycles with excellent long-term cycling stability and good rate capability when used as anode materials for lithium ion batteries.The present work definitely reveals the advantages of 2D heterostructures featured with a surface-to-surface stack between two different nanosheets in energy storage and conversion devices.

Eliminating the electric field response in a perovskite heterojunction solar cell to improve operational stability

Intrinsic and extrinsic ion migration is a very large threat to the operational stability of perovskite solar cells and is difficult to completely eliminate due to the low activation energy of ion migration and the existence of internal electric field.We propose a heterojunction route to help suppress ion migration,thus improving the operational stability of the cell from the perspective of eliminating the electric field response in the perovskite absorber.A heavily doped p-type(p^(+))thin layer semiconductor is introduced between the electron transporting layer(ETL)and perovskite absorber.The heterojunction charge depletion and electric field are limited to the ETL and p^(+)layers,while the perovskite absorber and hole transporting layer remain neutral.The p^(+)layer has a variety of candidate materials and is tolerant of defect density and carrier mobility,which makes this heterojunction route highly feasible and promising for use in practical applications.

Small molecular non-fullerene electron acceptors for P3HT-based bulk-heterojunction solar cells

Three small molecules with the same arms and different cores of perylene diimide(PDI)or indaceno[2,1-b:6,5-b']dithiophene(IDT)were designed and synthesized as the acceptor materials for P3HT-based bulk-heterojunction(BHJ)solar cells.The impacts of the different cores on the optical absorption,electrochemical properties,electron mobility,film morphology,photoluminescene characteristics,and solar cell performance were thoroughly studied.The three compounds possess a broad absorption covering the wavelength range of 400–700 nm and relatively low lowest unoccupied molecular orbital(LUMO)energy levels of?3.86,?3.81 and?3.99 eV.The highest power conversion efficiency of 0.82%was achieved for the BHJ solar cells based on SM3 as the acceptor material,the compound with a PDI core.

Suppression of Sn^(2+) and Lewis acidity in SnS_(2)/black phosphorus heterostructure for ppb-level room temperature NO_(2) gas sensor

The selective detection of harmful gases is of great significance to human health and air quality,triggering the need for special customizations of sensing material structure.In this study,we prepared a novel Sn S_(2)/black phosphorus(BP)two-dimensional(2D)-2D heterostructure via the in situ hydrothermal growth of Sn S_(2)nanosheets on exfoliated BP lamellae for NO_(2)sensing applications.In the Sn S_(2)/BP composite,the holes with high oxidizability in p-type BP could oxidize Sn^(2+)into Sn^(4+),thus inhibiting the formation of Lewis acidic S vacancies.This Sn^(2+)/Lewis acidity suppression of the composite was further confirmed by X-ray photoelectron spectroscopy and acidic double-layer capacitance analyses,and promoted the adsorption and detection of acidic NO_(2).Owing to its valence and Lewis acidity engineering,the Sn S_(2)/BP heterostructure sensor could detect trace levels of NO_(2)as low as 100 ppb(parts per billion)with high response,fast response/recovery,good stability,and selectivity at room temperature.The high absorption energy of NO_(2)(à0.74 e V),as indicated by the density functional theory calculations,suggests that NO_(2)was chemically adsorbed on the Sn S_(2)/BP surface,which was also evidenced by the in situ Raman spectroscopy results.This work opens up interesting opportunities for the rational design of highly efficient NO_(2)gas sensors through Lewis acidity modification and interface engineering.

In situ construction of heterostructured bimetallic sulfide/phosphide with rich interfaces for high-performance aqueous Zn-ion batteries

It is still challenging to develop suitable cathode structures for high-rate and stable aqueous Zn-ion batteries.Herein,a phosphating-assisted interfacial engineering strategy is designed for the controllable conversion of NiCo_(2)S_(4) nanosheets into heterostructured NiCoP/NiCo_(2)S_(4) as the cathodes in aqueous Zn-ion batteries.The multicomponent heterostructures with rich interfaces can not only improve the electrical conductivity but also enhance the diffusion pathways for Zn-ion storage.As expected,the NiCoP/NiCo_(2)S_(4) electrode has high performance with a large specific capacity of 251.1 mA h g^(−1) at a high current density of 10 A g^(−1) and excellent rate capability(retaining about 76%even at 50 A g^(−1)).Accordingly,the Zn-ion battery using NiCoP/NiCo_(2)S_(4) as the cathode delivers a high specific capacity(265.1 mA h g^(−1) at 5 A g^(−1)),a long-term cycling stability(96.9%retention after 5000 cycles),and a competitive energy density(444.7W h kg^(−1) at the power density of 8.4 kW kg^(−1)).This work therefore provides a simple phosphating-assisted interfacial engineering strategy to construct heterostructured electrode materials with rich interfaces for the development of high-performance energy storage devices in the future.

Interface energetics and engineering of organic heterostructures in organic photovoltaic cells

The reliable information about interface energetics of organic materials, especially the energy level alignment at organic heterostructures is of pronounced importance for unraveling the photon harvesting and charge separation process in organic photovoltaic(OPV) cells. This article provides an overview of interface energetics at typical planar and mixed donor-acceptor heterostructures, perovskite/organic hybrid interfaces, and their contact interfaces with charge collection layers. The substrate effect on energy level offsets at organic heterostructures and the processes that control and limit the OPV operation are presented. Recent efforts on interface engineering with electrical doping are also discussed.

Fabrication and characterization of amorphous ITO/p-Si heterojunction solar cell

Amorphous indium-tin-oxide(a-ITO) film was deposited by radio-frequency(RF) magnetron sputtering at 180°C substrate temperature on the texturized p-Si wafer to fabricate a-ITO/p-Si heterojunction solar cell.The microstructural,optical and electrical properties of the a-ITO film were characterized by XRD,SEM,XPS,UV-VIS spectrophotometer,four-point probe and Hall effect measurement,respectively.The electrical properties of heterojunction were investigated by I-V measurement,which reveals that the heterojunction shows strong rectifying behavior under a dark condition.The ideality factor and the saturation current density of this diode are 2.26 and 1.58×10-4 A cm-2,respectively.And the value of IF/IR(IF and IR stand for forward and reverse currents,respectively) at 1 V is found to be as high as 21.5.For the a-ITO/p-Si heterojunction solar cell,the a-ITO thin film acts not only as an emitter layer,but also as an anti-reflected coating film.The conversion efficiency of the fabricated a-ITO/p-Si heterojunction cell is approximately 1.1%,under 100 mW cm-2 illumination(AM1.5 condition).And the open-circuit voltage(Voc),short-circuit current density(J SC),filll factor(FF) are 280 mV,9.83 mA cm 2 and 39.9%,respectively.Because the ITO film deposited at low temperature is amorphous,it can effectively reduce the interface states between ITO and p-Si.The barrier height and internal electric field,which is near the surface of p-Si,can effectively be enhanced.Thus we can see the great photovoltaic effect.

Enhanced visible-light photocatalytic activity of a g-C_3N_4/m-LaVO_4 heterojunction: band offset determination

Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts. Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of efficient photocatalysts. We used a typical in situ-method to prepare diverse graphite-phase carbon nitride(g-C_3N_4)samples from melamine, thiourea, and a mixture thereof,and found that they exhibited band gaps between2.3–2.8 e V. From UV–Vis spectra and X-ray photoelectron spectroscopy measurements, we determined that the g-C_3N_4 samples exhibited different band gap values and valence band positions. On this basis, we constructed g-C_3N_4/m-La VO_4 heterojunctions with different band offsets. UV–Vis spectra and X-ray photoelectron spectroscopy measurements revealed that the valence band offsets(VBOs) of the different heterojunctions were similar, but their conduction band offsets(CBOs) were significantly different. Photocatalytic experiments revealed that the reaction rate was enhanced with an increase in the CBO value. Furthermore, the three-phase g-C_3N_4/g-C_3N_4/mLa VO_4 heterojunction composed of m-La VO_4 and mixed g-C_3N_4 showed the highest photocatalytic activity, which was mainly due to the construction of a multilevel structure. This work investigates the influence of the band offset on heterojunction photoelectrochemical properties and provides a new strategy to improve the photocatalytic activity by constructing multilevel structures.