浅论小型工作室航拍器的选择

图像单元的提升对于图片的拍摄意义重大,这个差距是使用堆栈以及HDR合成技术都难以消除的。笔者今年也开始了航拍川藏线的尝试,将拍摄经验汇聚在本文中,以得抛砖引玉之效。

I- VCurve Characterization of n +/p/p+ Silicon Solar Cell

The analysis of solar cell performance has been done by simulating the external I-V characteristics of n +/p/p + single crystal silicon solar cell under high light intensity and 1.5 air mass (AM). This method allows the maximization of solar cell efficiency. To fabricate low-cost n +/p/p + single crystal silicon solar cells, solid source of doped phosphorous and boron was used.

Traffic-prediction-assisted dynamic power saving mechanism for IEEE 802.16e wireless MANs

How to reduce the energy consumption powered mainly by battery to prolong the standby time is one of the crucial issues for IEEE 802.16e wireless MANs.By predicting the next downlink inter-packet arrival time,three traffic-prediction-assisted power saving mechanisms based on P-PSCI,i.e.,PSCI-PFD,PSCI-ED and PSCI-LD,were proposed.In addition,the corresponding adjustment strategies for P-PSCI were also presented when there were uplink packets to be transmitted during sleep mode.Simulation results reveal that compared with the sleep mode algorithm recommended by IEEE 802.16e,the proposed mechanism P-PSCI can improve both energy efficiency and packet delay for IEEE 802.16e due to the consideration of the traffic characteristics and rate changes.Moreover,the results also demonstrate that PSCI-PFD (a=-2) significantly outperforms PSCI-ED,PSCI-LD,and the standard sleep mode in IEEE 802.16e is in terms of energy efficiency and packet delay.

High Efficiency Polymer Solar Cells Technologies

The conjugated polymer-based solar cell is one of the most promising devices in search of sustainable, renewable energy sources in last decade. It is the youngest field in organic solar cell research and also is certainly the fastest growing one at the moment. In addition, the key factor for polymer-based solar cells with high-efficiency is to invent new materials. Organic solar cell has attracted significant researches and commercial interest due to its low cost in fabrication and flexibility in applications. However, they suffer from relatively low conversion efficiency. The summarization of the significance and concept of high efficiency polymer solar cell technologies are presented.

Analysis of an SME using Silicon and Flexible Organic Solar Cells as Replacements for Fossil Fuel Sources of Electricity in UK and Iraq

Currently, 86% of the energy originates from fossil fuelsforelectricity. These are expected to run out, causing severe environmental damage threatening future generations. The total impact of Small and Medium Enterprises （SMEs） on the economy is significant. Solar cells harness the sun＇s energy to generate electricity in an environmentally friendly manner. This study compares silicon solar cells to flexible Organic Photovoltaic solar cells （OPV） for electricity energy for a micro-business in the UK and Iraq. It shows that it is feasible to replace existing fossil fuel sources with solar cells in Iraq due to a greater amount of solar radiation striking the earth＇s surface. Flexible solar cells can replace a proportion of the energy requirements in the UK and a larger proportion in Iraq. Using existing 20% efficient solar cells, 28% and 83% of the energy requirements of the microbusiness can be replaced in UK and Iraq respectively. Assuming 20% efficiency for solar cells placed on windows, 74% and 220% of the energy requirements of UK and Kurdistan can be replaced respectively and the surplus stored.

Study of Back Contacts for CdTe Solar Cells

ZnTe/ZnTe∶Cu layer is used as a complex back contact. The parameters of CdTe solar cells with and without the complex back contacts are compared. The effects of un-doped layer thickness, doped concentration and post-deposition annealing temperature of the complex layer on solar cells performance are investigated.The results show that ZnTe/ZnTe∶Cu layer can improve back contacts and largely increase the conversion efficiency of CdTe solar cells. Un-doped layer and post-deposition annealing of high temperature can increase open voltage. Using the complex back contact, a small CdTe cell with fill factor of 73.14% and conversion efficiency of 12.93% is obtained.

Defect Detection in Raw Si Substrates Using Transmission Polarimetry

Inline characterization for fabrication of silicon wafer PV （photovoltaic） devices may be used to optimize device efficiencies, reduce their performance variance, and their cost of production. In this article, the frozen in strain from a variety of extended defects in silicon is shown to effect the polarization of light transmitted through a silicon substrate due to the photo-elastic effect. Transmission polarimetry on pre-fabricated silicon substrates may be used for identification of extended defects in the materials using a polarization analysis instrument. Instrumentation is proposed for detection of defects in raw silicon wafers for applications like raw silicon wafer sorting, scanning silicon bricks, and inline inspection prior to solar cell metallization. Such analysis may assist with gettering of silicon solar cells, may be implemented in the sorting and rejection procedures in PV device fabrication, and in general shows advantages for detection of defects in silicon wafer solar cell materials and devices.

Recent advances in producing hollow carbon spheres for use in sodium−sulfur and potassium−sulfur batteries

Sodium-sulfur(Na-S)and potassium-sulfur(K-S)batteries for use at room temperature have received widespread attention because of the abundance and low cost of their raw materials and their high energy density.However,their development is restricted by the shuttling of polysulfides,large volume expansion and poor conductivity.To overcome these obstacles,an effective approach is to use carbon-based materials with abundant space for the sulfur that has sulfiphilic sites to immobilize it,and a high electrical conductivity.Hollow carbon spheres(HCSs)with a controllable structure and composition are promising for this purpose.We consider recent progress in optimizing the electrochemical performance of Na-/K-S batteries by using these materials.First,the advantages of HCSs,their synthesis methods,and strategies for preparing HCSs/sulfur composite materials are reviewed.Second,the use of HCSs in Na-/K-S batteries,along with mechanisms underlying the resulting performance improvement,are discussed.Finally,prospects for the further development of HCSs for metal−S batteries are presented.

External Quantum Efficiency of Quantum Well Solar Cells

The external quantum efficiency of quantum well solar cells （QWSCs） is compared with the control cells without multi-quantum wells. The QWSCs extend the absorption spectrum from 870 to 1000nm. When the wavelength is below 680nm,the external quantum efficiency of the QWSCs is lower than that of the control cells, but when the wavelength is above 680nm, the external quantum efficiency of the QWSCs is higher than that of the control cells. The possible reasons for this phenomenon are discussed. Basing on the experimental data,the possibility of substituting the middle cells of conventional triple-junction solar cells with the QWSCs to improve their performance is also discussed.

Photovoltaic efficiency enhancement of polycrystalline silicon solar cells by a highly stable luminescent film

Si-based solar cells have dominated the entire photovoltaic market,but remain suffering from low power conversion efficiency(PCE),partly because of the poor utilization of ultraviolet(UV)light.Europium(III)(Eu^3+)complexes with organic ligands are capable of converting UV light into strong visible light,which makes them ideal light converter to increase the efficiency of solar cells.However,the low stability of such complexes seriously hampers their practical applications.In this work,we report a highly stable and luminescent ethylene-vinyl acetate(EVA)copolymer film consisting of a Eu^3+complex as a down-shift material,Eu(ND)4 CTAC(ND=4-hydroxy-2-methyl-1,5-naphthyridine-3-carbonitrile,CTAC=hexadecyl trimethyl ammonium chloride),coating of which onto the surface of large area polycrystalline silicon solar cells(active area:110 cm^2)results in an increase of PCE from 15.06%to 15.57%.Remarkable stability of the luminescent film was also demonstrated under lightsoaking test for 500 h,and no obvious luminescence degradation can be observed.The remarkable enhancement of the conversion efficiency by 0.51%absolute on such a large active area,together with the high stability of the luminescent film,demonstrates a prospect for the implementation of the films in photovoltaic industry.

Hollow-in-hollow carbon spheres with hollow foam-like cores for lithium-sulfur batteries

Lithium-sulfur batteries have attracted increasing attention because of their high theoretical capadty. Using sulfur/carbon composites as the cathode materials has been demonstrated as an effective strategy to optimize sulfur utilization and enhance cycle stability as well. In this work hollow-in-hollow carbon spheres with hollow foam-like cores （HCSF@C） are prepared to improve both capability and cycling stability of lithium-sulfur batteries. With high surface area and large pore volumes, the loading of sulfur in HCSF@C reaches up to 70 wt.%. In the resulting S/HCSF@C composites, the outer carbon shell serves as an effective protection layer to trap the soluble polysulfide intermediates derived from the inner component. Consequently, the S/HCSF@C cathode retains a high capacity of 780 mAh/g after 300 cycles at a high charge/discharge rate of 1 A/g.

Li_2O_2 oxidation: the charging reaction in the aprotic Li-O_2 batteries

Aprotic Li-O2 battery has attracted a great deal of interest because of its high theoretical energy density that is far beyond what the best Li-ion technologies can achieve.However, the present Li-O2 batteries suffer from the low energy efficiency that is limited mainly by the high overpotentials required to re-oxidize Li2O2, the discharge product. Over the past few years, considerable research efforts have been devoted to the understanding of the Li2O2 oxidation reactions. Here, we summarize the results obtained from the fundamental study of the Li2O2 oxidation, including its morphology, reaction route, kinetics, the initial location upon oxidation and the charge transport within Li2O2. A better mechanistic understanding of the Li2O2 oxidation reaction will provide a solid foundation for the realization of practical Li-O2 cells with a higher energy efficiency.

Identifying the functional groups effect on passivating perovskite solar cells

Many organic molecules with various functional groups have been used to passivate the perovskite surface for improving the efficiency and stability of perovskite solar cell(PSCs).However,the intrinsic attributes of the passivation effect based on different chemical bonds are rarely studied.Here,we comparatively investigate the passivation effect among 12 types of functional groups on para-tertbutylbenzene for PSCs and find that the open circuit voltage(VOC) tends to increase with the chemical bonding strength between perovskite and these passivation additive molecules.Particularly,the paratert-butylbenzoic acid(tB-COOH),with the extra intermolecular hydrogen bonding,can stabilize the surface passivation of perovskite films exceptionally well through formation of a crystalline interlayer with water-insoluble property and high melting point.As a result,the tB-COOH device achieves a champion power conversion efficiency(PCE) of 21.46%.More importantly,such devices,which were stored in ambient air with a relative humidity of ~45%,can retain 88% of their initial performance after a testing period of more than 1 year(10,080 h).This work provides a case study to understand chemical bonding effects on passivation of perovskite.

Ni3S2@S-carbon nanotubes synthesized using NiS2 as sulfur source and precursor for high-performance sodium-ion half/full cells

Nickle sulfides are attractive anode materials for sodium-ion batteries(SIBs) due to their rich structures and natural abundance. However, their applications are greatly hindered by the large volume expansion and poor cycling properties. The introduction of hollow structures and heteroatom-doped carbon layers are effective ways to solve these issues. Here, nitrogen, sulfur co-doped carbon coated Ni3S2(abbreviated as, Ni3S2@NSC) nanotubes were prepared by a novel templating route. During the annealing process, NiS2 acts as both a precursor to Ni3S2 and an S-doped sulfur source.No additional sulfur source was used during the S-doping procedure, suggesting an atomically economic synthesis process. As anodes for sodium-ion half-cells, Ni3S2@NSCs exhibited high discharge capacity of 481 mA h g^-1 at 0.1 A g^-1 after 100 cycles with exceptional capacity retention of 98.6%.Furthermore, they maintained excellent rate capability of 318 mA h g^-1 even at elevated current density of 5 A g^-1. Sodium-ion full-cells assembled from the Ni3S2@NSC anodes and Na3V2(PO4)3(NVP@C) cathodes also presented superior capacities and cyclabilities. These features can be attributed to the N, S co-doped carbon coated hollow structure that provided sufficient contact between the electrode and electrolyte,enhanced surface ion storage performance(capacitive effect),and improved structural stability of electrode materials.

Sn precursor enables 12.4%efficient kesterite solar cell from DMSO solution with open circuit voltage deficit below 0.30 V

The limiting factor preventing further performance improvement of the kesterite(sulfide Cu2ZnSnS4(CZTS),selenide Cu2ZnSnS4(CZTSe),and their alloying Cu2Zn Sn(S,Se)4(CZTSSe))thin film solar cells is the large open-circuit voltage deficit(Voc,def)issue,which is 0.345 V for the current world record device with an efficiency of 12.6%.In this study,SnCl4 and Sn Cl2·2H2O were respectively used as tin precursor to investigate the Voc,def issue of dimethyl sulfoxide(DMSO)solution processed CZTSSe solar cells.Different complexations of tin compounds with thiourea(Tu)and DMSO resulted in different reaction pathways from the solution to the absorber material and thus dramatic differences in photovoltaic performance.The coordination of Sn^2+with Tu led to the formation of SnS,ZnS and Cu2S in the precursor film,which converted to selenides first and then fused to CZTSSe,resulting in poor film quality and device performance.The highest efficiency obtained from this film was 8.84%with a Voc,def of 0.391 V.The coordination of Sn4+with DMSO facilitated direct formation of CZTS phase in the precursor film which directly converted to CZTSSe during selenization,resulting in compositional uniform absorber and high device performance.A device with an active area efficiency of 12.2%and a Voc,def of 0.344 V was achieved from the Sn^4+solution processed absorber.Furthermore,CZTSSe/Cd S heterojunction heat treatment(JHT)significantly improved the performance of the Sn^4+device but had slightly negative effect on the Sn2+device.A champion CZTSSe solar cell with a total area efficiency of 12.4%(active area efficiency of 13.6%)and a low Voc,def of 0.297 V was achieved from the Sn^4+solution.Our results demonstrate the preformed uniform CZTSSe phase enabled by Sn4+precursor is the key for the highly efficient CZTSSe absorber.The lowest Voc,def and high efficiency achieved here shines new light on the future of CZTSSe solar cell.

15.3% efficiency all-small-molecule organic solar cells enabled by symmetric phenyl substitution

Synergistic optimization of donor-acceptor blend morphologyis a hurdle in the path of realizing efficient non-fullerene small-molecule organic solar cells(NFSMOSCs)due to the anisotropic conjugated backbones of both donor and acceptor.Therefore,developing a facile molecular design strategy to effectively regulate the crystalline properties of photoactive materials,and thus,enable the optimization of blend morphology is of vital importance.In this study,a new donor molecule B1,comprising phenyl-substituted benzodithiophene(BDT)central unit,exhibits strong interaction with the non-fullerene acceptor BO-4 Cl in comparison with its corresponding thiophene-substituted BDT-based material,BTR.As a result,the B1 is affected and induced from an edgeon to a face-on orientation by the acceptor,while the BTR and the acceptor behave individually for the similar molecular orientation in pristine and blend films according to grazing incidence wide angle X-ray scattering results.It means the donor-acceptor blend morphology is synergistically optimized in the B1 system,and the B1:BO-4 Cl-based devices achieve an outstanding power conversion efficiency(PCE)of 15.3%,further certified to be 15.1%by the National Institute of Metrology,China.Our results demonstrate a simple and effective strategy to improve the crystalline properties of the donor molecule as well as synergistically optimize the morphology of the all-small-molecule system,leading to the high-performance NFSM-OSCs.

Band alignment towards high-efficiency NiOx-based Sn-Pb mixed perovskite solar cells

Narrow-bandgap tin-lead(Sn-Pb)mixed perovskite solar cells(PSCs)play a key role in constructing perovskite tandem solar cells that are potential to overpass Shockley-Queisser limit.A robust,chemically stable and lowtemperature-processed hole transporting layer(HTL)is essential for building high-efficiency Sn-Pb solar cells and perovskite tandem solar cells.Here,we explore a roomtemperature-processed NiOx(L-NiOx)HTL based on nanocrystals(NCs)for Sn-Pb PSCs.In comparison with hightemperature-annealed NiOx(H-NiOx)film,the L-NiOx film shows deeper valence band and lower trap density,which increases the built-in potential and reduces carrier recombination,leading to a power conversion efficiency of 18.77%,the record for NiOx-based narrow-bandgap PSCs.Furthermore,the device maintains about 96%of its original efficiency after 50 days.This work provides a robust and room-temperatureprocessed HTL for highly efficient and stable narrow-bandgap PSCs.

Fabrication of Large Area High Density, Ultra-Low Reflection Silicon Nanowire Arrays for Efficient Solar Cell Applications

High density vertically aligned and high aspect ratio silicon nanowire （SiNW） arrays have been fabricated on a Si substrate using a template and a catalytic etching process. The template was formed from polystyrene （PS） nanospheres with diameter 30-50 nm and density 10^10/cm^2, produced by nanophase separation of PS-containing block-copolymers. The length of the SiNWs was controlled by varying the etching time with an etching rate of 12.5 nm/s. The SiNWs have a biomimetic structure with a high aspect ratio （-100）, high density, and exhibit ultra-low reflectance. An ultra-low reflectance of approximately 0.1% was achieved for SiNWs longer than 750 nm. Well-aligned SiNW/poly（3,4-ethylenedioxy-thiophene）：poly（styrenesulfonate） （PEDOT：PSS） heterojunction solar cells were fabricated. The n-type silicon nanowire surfaces adhered to PEDOT：PSS to form a core-sheath heterojunction structure through a simple and efficient solution process. The large surface area of the SiNWs ensured efficient collection of photogenerated carriers. Compared to planar cells without the nanowire structure, the SiNW/PEDOT：PSS heterojunction solar cell exhibited an increase in short-circuit current density from 2.35 mA/cm^2 to 21.1 mA/cm^2 and improvement in power conversion efficiency from 0.4% to 5.7%.

Lamella-like electrode with high Br_(2)-entrapping capability and activity enabled by adsorption and spatial confinement effects for brominebased flow battery

Bromine-based flow batteries(Br-FBs)are well suitable for stationary energy storage owing to their high energy density and low cost.However,their power density and lifespan are limited by relatively low reaction kinetics of Br_(2)/Br-couple and serious self-discharge caused by bromine migration.Herein,lamella-like porous carbon nitride nanosheets(PCNS)with adsorption and spatial confinement effects are used to modify cathodes for Br-FBs.The large specific surface area and plentiful N-containing groups enable PCNS with excellent adsorption capacity,which captures bromine species into the pores on PCNS layers.The captured bromine species is subsequently confined in PCNS interlayers due to the strong interaction between bromine species and N-containing groups,thus effectively depressing bromine diffusion/migration.Moreover,the strong bromine adsorption capacity significantly improves the electrochemical activity of PCNS.Consequently,a zinc-bromine flow battery(ZBFB)employing PCNS-modified cathode achieves a high current density of 180 m A cm^(-2),with an ultra-high coulombic efficiency of 99.22%.It also exhibits better self-discharge performance and a long cycle life of 500 cycles.Furthermore,a complexing agent-free ZBFB is successfully realized based on the superior bromineentrapping/retaining capacity of the PCNS-modified cathode.Consequently,this work provides a promising strategy toward electrode modifications for high-performance and long-lifespan Br-FBs.

Optimizing the component ratio of PEDOT:PSS by water rinse for high efficiency organic solar cells over 16.7%

For the state-of-the-art organic solar cells(OSCs),PEDOT:PSS is the most popularly used hole transport material for the conventional structure.However,it still suffers from several disadvantages,such as low conductivity and harm to ITO due to the acidic PSS.Herein,a simple method is introduced to enhance the conductivity and remove the additional PSS by water rinsing the PEDOT:PSS films.The photovoltaic devices based on the water rinsed PEDOT:PSS present a dramatic improvement in efficiency from 15.98%to 16.75%in comparison to that of the untreated counterparts.Systematic characterization and analysis reveal that although part of the PEDOT:PSS is washed away,it still leaves a smoother film and the ratio of PEDOT to PSS is higher than before in the remaining films.It can greatly improve the conductivity and reduce the damage to substrates.This study demonstrates that finely modifying the charge transport materials to improve conductivity and reduce defeats has great potential for boosting the efficiency of OSCs.