丝网印刷法制备染料敏化太阳能电池光电性能的研究

采用水热法制备TiO2纳米颗粒,将获得的TiO2纳米颗粒制备成胶体,采用丝网印刷法在FTO表面刷涂制备染料敏化太阳能电池（DSSC）光阳极,通过扫描电子显微镜对电极表征和电池光电性能测试,探讨印刷层数及入射光强对DSSC光电性能的影响,实验结果表明,将制备的光阳极组装成电池后具有较好的光电性能,当印刷层数为8层、光强为80W／m2时,电池取得最好的光电性能。     

Optically tunable intramolecular charge transfer dyes for vacuum deposited bulk heterojunction solar cells

We present the tunability of the photophysical and electrochemical properties of a series of intramolecular charge transfer compounds by facile molecular design and synthesis. The photovoltaic performances based on these sublimable materials and C(60) bulk heterojunction cells are compared and reported. The structural modification of the charge transfer dyes altered not only the electronic properties, but also the morphology of the bulk heterojunction thin films, as revealed by AFM and SEM studies. Addition of PEDOT:PSS between the ITO and the photoactive layer improved the hole injection from the photosensitizer into the anode, and the overall power conversion efficiency is also enhanced.     

体相异质结型有机太阳能电池的研究进展

基于电子给/受体共混体系制备的体相异质结型有机太阳能电池是一种低耗、高效的有机光伏器件.作为器件核心,光电转化共混活性层的质量优劣会直接影响器件的能量转换效率.研究发现,不同的给/受体材料组成、2种材料的共混比例、共溶剂的选择以及器件的热退火处理等因素都可影响到活性层质量.结合上述研究热点,综述了体相异质结型有机太阳能电池近年来的研究进展,阐述了该研究领域下一步发展的重点、趋势及前景.     

Solution-processed inverted organic solar cell using V2O5 hole transport layer and vacuum free EGaIn anode

In this study, the sol–gel V₂O₅ derived by a hydrothermal method to replace the PEDOT:PSS which is a hole transport layer between organic active layer and two different anodes in inverted organic solar cells with TiO₂ as an electron transport layer was investigated. The power conversion efficiencies of inverted organic photovoltaic cells increased approximately twofold with using V₂O₅ instead of PEDOT:PSS on top of the photoactive layer. It was demonstrated that the power conversion efficiencies of inverted organic solar cells prepared with V₂O₅ solution which was diluted with isopropanol in certain proportions by volume were decreased by increasing ratio of isopropanol in total volume. It was reported for the first time that the inverted organic photovoltaic cells prepared using V₂O₅ interlayer and Eutectic Gallium–Indium alloy which was prepared using vacuum free simple brush-painted method and can be used as anode electrode as Ag electrode.     

Synthesis of SnS nanoparticles by SILAR method for quantum dot-sensitized solar cells

SnS-sensitized TiO2 electrodes were applied in quantum dot-sensitized solar cells (QDSSCs) which are environmentally more favorable than conventional Cd or Pb-chalcogenide-sensitized electrodes. SnS nanoparticles were well-distributed over the surface of TiO2 nanoparticles by the successive ionic layer adsorption and reaction (SILAR) method. Deposited SnS nanoparticles had diameter about 3 nm. Under AM1.5 irradiation with 100 mW/cm2 light intensity (at 1 sun), the energy conversion efficiency of obtained cells reached a value of 0.21% (0.25 cm2) at SILAR coating cycles of 5. In addition, the photovoltaic performance was improved by additional ZnS coating on the surface of SnS-sensitized TiO2 electrodes.     

Aqueous Metal Oxide Inks for Modifying Electrode Work Function in Polymer Solar Cells

A method to prepare aqueous metal oxide inks for tuning the work function (WF) of electrodes is demonstrated. Thin films prepared from the metal oxide ink based on vanadium oxide (V₂O₅) nanoparticles are found to increase the WF of an indium‐tin‐oxide (ITO) electrode. ITO substrates modified with V₂O₅ films are applied as a hole selective layer (HSL) in polymer solar cells (PSCs) using a poly(3‐hexylthiophene) and [6,6]‐phenyl‐C61 butyric acid methyl ester blend as a photoactive layer. The PSCs prepared with V₂O₅‐modified ITO show better device performance, achieving a power conversion efficiency of 3.6%, demonstrating 15% enhancement compared to conventional ITO/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT‐PSS) based devices. Furthermore, ITO/V₂O₅‐modified devices exhibit better ambient stability with 60% improvement in device lifetime than those using PEDOT:PSS as an HSL. This solution‐processable and highly stable WF‐modifying metal oxide film can be a potential alternative material for engineering interfaces in optoelectronic devices.     

Pressing effect in polymer solar cells with bulk heterojunction nanolayers

We report the effect of pressing light-absorbing layers on the performance of polymer solar cells. The light-absorbing active layer was prepared on the transparent conducting oxide coated substrates from solutions that contain a mixture of regioregular poly(3-hexylthiophene) and soluble fullerene molecules. The active layers were pressed using a home-built micro-press system by controlling temperature and pressure, followed by the top electrode deposition. The surface of the active layers pressed was examined using atomic force microscope, while the photovoltaic characteristics of devices were measured under simulated solar light illumination (air mass 1.5 G, 100 mW/cm2). Results showed that the dark current of devices was noticeably increased by pressing the active layer without respect to the pressing temperature. The highest power conversion efficiency was achieved for the device with the active layer pressed under 10 kgf at 70 degrees C. The result was explained in terms of surface morphology and thermophysical effect.     

A heterojunction photovoltaic cell based on a mixture of silane copolymer with C<Subscript>70</Subscript> fullerene derivative

Heterojunction photovoltaic cells with a photoactive layer composed of a mixture of a silane copolymer with a fullerene derivative PC₇₀BM have been fabricated, and their working characteristics have been measured. Data obtained by cyclic voltammetry were used to construct the energy level diagram for the cell components. Analysis of the diagram and photoelectric characteristics of the photovoltaic cell made it possible to find ways to improve its efficiency.     

染料敏化太阳能电池无FTO煤基炭对电极的研究

分别以气煤、焦煤、瘦煤为原料制备了低成本、高性能煤基炭对电极(counter electrodes, CEs), 并使用煤基炭CE同时代替导电玻璃基底和催化层, 分别考察了浸渍和表面修饰对煤基炭CE结构和光电性能的影响。采用X射线衍射、扫描电镜和电化学阻抗谱等表征手段, 对煤基炭CE的结构和性能进行了表征。结果表明: 浸渍后煤基炭CE形成了底层致密表层多孔的一体化结构; 经过表面修饰的煤基炭CE表现出良好的光电性能, 其开路电压(V_oc)、短路电流密度(J_sc)和填充因子(FF)分别为0.79 V、13.48 mA/cm²和0.67, 光电转化效率(η)达到了7.16%, 与传统Pt电极的效率相当, 比石墨电极效率提高30%。煤基炭CE是传统Pt/FTO电极的良好替代材料。     

Pt-TiO2纳米管电极的制备及电催化性能

采用电化学阳极氧化-阴极还原法制备Pt-TiO2纳米管电极.扫描电镜(SEM)结果显示TiO2纳米管平均管径100nm,管长470nm,管壁厚20nm,且其比表面积大,同时纳米Pt微粒分散在TiO2纳米管上,且粒径细小,Pt微粒充分裸露,使得Pt-TiO2纳米管电极活性点多,电催化性能高.对甲醇的电催化性能测试表明:同纯Pt电极和Pt-TiO2电极(Pt微粒固定在TiO2致密膜上)相比,Pt-TiO2纳米管电极对甲醇具有更高的电催化活性,其氧化峰电流密度是在纯Pt片电极上的20倍以上.     

Enhancing the photovoltaic performances of dye-sensitized solar-cells by modifying the TiO2 electrode-sensitized dye interface

Enhanced photovoltaic performances of N719 dye-sensitized solar-cells were achieved by modifying the titanium oxide (TiO₂) electrode-sensitized dye interface. Surface of TiO₂ thin film electrode was coated with a calcium oxide (CaO) or lithium fluoride (LiF) thin layer, respectively, in a thermal deposition chamber. As compared to a cell using a bare TiO₂ nanoparticle (NTP) electrode, the solar energy conversion efficiency (η)? was enhanced by 15.1% and 12.8% for the surface of a NTP electrode coated with CaO and LiF, respectively. Moreover, for the surface of a TiO₂ nanotube electrode respectively coated with CaO and LiF, the efficiency was enhanced by 4.8% and 11.6%. This increase in efficiency is attributed to an increase in the adsorption of N719 dye on the CaO or LiF coated TiO₂ thin film electrodes, and the formation of a potential barrier by a CaO or LiF interlayer at the TiO₂ electrode-sensitized dye interface.     

The photovoltaic effect and charge carrier mobility in layered compositions of bithiophene or related rotaxane copolymer with C<Subscript>70</Subscript> fullerene derivative

Organic photovoltaic cells with a bulk heterojunction have been manufactured in which the photoactive layer consists of a mixture of bithiophene copolymer or related rotaxane with a fullerene derivative (PC₇₀BM). The mobility of charge carriers in photoactive layers has been determined, the current–voltage characteristics of photovoltaic cells have been measured, and the energy level diagram of cell components has been constructed. It is established that the polyrotaxane component (macrocycle) insulates a part of thiophene fragments of the macromolecule, thus hindering the transport of carriers and leading to large energy losses for exciton dissociation, which results in a decreasing photovoltaic effect.     

Near-infrared responsive PbS-sensitized photovoltaic photodetectors fabricated by the spin-assisted successive ionic layer adsorption and reaction method

A PbS-sensitized photovoltaic photodetector responsive to near-infrared (NIR) light was fabricated by depositing monolayered PbS nanoparticles on a mesoporous TiO(2) (mp-TiO(2)) film via the spin-assisted successive ionic layer adsorption and reaction (SILAR) method. By adjusting the size and morphology of the PbS nanoparticles through repeated spin-assisted SILAR cycles, the PbS-sensitized photovoltaic photodetector achieved an external quantum efficiency of 9.3% at 1140 nm wavelength and could process signals up to 1 kHz.     

CuPc/C60薄膜太阳能电池的制备及膜厚对其光电性能的影响

本文采用CuPc作为电子给体,C60作为电子受体制备了ITO/CuPc/C60/Al异质结太阳能电池。实验表明器件中活性层(CuPc/C60)对太阳能电池的光电性能有很大的影响。主要原因是有机物的激子扩散长度大约是十几纳米左右,产生的激子大多数在未到达异质结之前就已经复合。本文讨论了活性层(CuPc/C60)的厚度比,并获得其最优比例。     

Charge storage variations of organic memory devices fabricated by using C60 molecules embedded in an insulating polymer layer with Au and Al electrodes

Organic memory devices based on a hybrid poly(4-vinyl phenol) (PVP) layer containing Buckminster-fullerene (C60) were formed by using a spin coating method. Capacitance-voltage measurements on Al/C60 embedded in PVP layer/p-Si (100) devices at 300 K showed a hysteresis with a large flatband voltage shift due to the existence of C60 molecules, indicative of the charge storage in the C60 molecules. The magnitude of the flat-band voltage shift for the memory devices with a hybrid active layer consisting of PVP and C60 was significantly affected by the type of electrode. The endurance time of the organic memory device fabricated utilizing C60 nanoparticles embedded in the PVP layer at 300 K was approximately 10 years, indicative of excellent memory endurance ability.     

Influence of the size-controlled TiO<Subscript>2</Subscript> nanotubes fabricated by low-temperature chemical synthesis on the dye-sensitized solar cell properties

Titanium dioxide nanotubes (TiO₂ NTs) with various sizes have been prepared by low-temperature chemical synthesis using commercial anatase TiO₂ particles with different crystallite size in NaOH solution and used as a photoelectrode in a dye-sensitized solar cell (DSSC). The relationship between the physicochemical properties of electrode materials and photovoltaic performance was investigated. The electrodes made from modified TiO₂ NTs showed a strong dependency on their specific surface area and resultant amount of dye adsorption; the surface area decreased with increase in the diameter of the NT from 9.8 to 23.6 nm. The conversion efficiency of the cell made from TiO₂ NT, 12.9 nm in diameter, was enhanced by 12% compared to that of the smallest NT. These results suggested that the photovoltaic performance improved by the suppression of photogenerated charge recombination in spite of a 25.3% reduction in the specific surface area. In addition, larger TiO₂ NTs could be utilized as a scattering layer on the top of the TiO₂ nanoparticulate working electrode. It was observed that this controlled TiO₂ photoelectrode architecture exhibited enhanced conversion efficiency without TiCl₄ treatment.     

Effect of surface fluorination of TiO2 particles on photocatalitytic activity of a hybrid multilayer coating obtained by sol-gel method

A multilayer photoactive coating containing surface fluorinated TiO(2) nanoparticles and hybrid matrices by sol gel approach based on renewable chitosan was applied on poly(lactic acid) (PLA) film by a step wise spin-coating method. The upper photoactive layer contains nano-sized functionalized TiO(2) particles dispersed in a siloxane based matrix. For the purpose of improving TiO(2) dispersion at the air interface coating surface, TiO(2) nanoparticles were modified by silane coupling agent 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FTS) with fluoro-organic side chains. An additional hybrid material consisting of chitosan (CS) cross-linked with 3-glycidyloxypropyl trimethoxy silane (GOTMS) was applied as interlayer between the PLA substrate and the upper photoactive coating to increase the adhesion and reciprocal affinity. The multilayer TiO(2)/CS-GOTMS coatings on PLA films showed a thickness of ~4-6 μm and resulted highly transparent. Their structure was exhaustively characterized by SEM, optical microscope, UV-vis spectroscopy and contact angle measurements. The photocatalytic activity of the multilayer coatings were investigated using methyl orange (MeO) as a target pollutant; the results showed that PLA films coated with surface fluorinated particles exhibit higher activity than films with neat particles, because of a better dispersion of TiO(2) particles. The mechanical properties of PLA and films coated with fluorinated particles, irradiated by UV light were also investigated; the results showed that the degradation of PLA substrate was markedly suppressed because of the UV adsorptive action of the multilayer coating.     

Light-assisted synthesis of Pt-Zn porphyrin nanocomposites and their use for electrochemical detection of organohalides

Pt-Zn porphyrin nanocomposites have been synthesized using zinc porphyrin and dihydrogen hexachloroplatinate in the presence of light and ascorbic acid. TEM and AFM imaging revealed that Pt nanoparticles with an average diameter of approximately 3.5 nm were embedded within the Zn porphyrin matrix. The glassy carbon electrode was modified with Nafion-stabilized Pt-Zn porphyrin nanocomposites and used for dehalogenation of carbon tetrachloride, chloroform, pentachlorophenol, chlorobenzene, and hexachlorobenzene as five test models. The Pt-Zn porphyrin nanocomposite-modified electrode exhibited catalytic activity for the reduction of organohalides at -1.0 V versus Ag/AgCl. Raman signatures confirmed the dehalogenation of chlorobenzene by the nanocomposite-modified electrode. The above two aliphatic and three aromatic organohalides had detection limits of 0.5 microM with linearity up to 8 microM. The modified electrode was good for at least 80 repeated measurements of 4 microM chlorobenzene with a storage stability of 1 month at room temperature. The deactivation of the electrode activity was associated with the loss of platinum nanoparticles from the nanocomposite structure.     

Is dye mixture more suitable rather than single dye to fabricate dye sensitized solar cell?

The steady state and time resolved spectroscopic studies reveal that two xanthene dyes Rhodamine 6G (R6G) and Rhodamine B (RB), used in the present investigations, form ground state hydrogen -bonded complexes with meso-tetrakis(4-carboxyphenyl) porphyrin (TCPP). However, it is apparent that upon photoexcitation the H-bonding complexes formed in the ground state decompose into the individual reacting components. This presumption was confirmed from the observation of the presence of only static quenching mode in the steady state fluorescence of the dyes in presence of porphyrin. The photoelectrochemical properties of the free dyes and the mixtures of each dye with porphyrin are investigated by measuring incident photon-to-current conversion efficiency (IPCE) using ZnO electrode and also with TiO2 electrode. It is seen that Rhodamine B-porphyrin mixture has attained maximum IPCE among the four samples studied at approximately 550 nm using ZnO electrode. Using TiO2 electrode, slight improvement in the value of IPCE was found for the same mixture. Therefore Rhodamine B-porphyrin mixture may act as a good sensitizer for converting solar energy to electrical energy.     

Transparent Nanowire Network Electrode for Textured Semiconductors

This work presents an inexpensive and easily manufacturable, highly conductive and transparent nanowire network electrode for textured semiconductors. It is based on lines of silver nanoparticles transformed into a nanowire network by microwave or furnace sintering. The nanonetwork electrode on crystalline silicon is demonstrated experimentally, with the nanoparticles self‐assembling in the valleys between the pyramids of the textured surface. Optical experiments show that this conductive nanowire network electrode can be essentially ‘invisible’ when covered with the conventional anti‐reflection coating (ARC), and thus could be employed in photovoltaic applications.