• Title/Summary/Keyword: Dyes-sensitized solar cells

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Highly Efficient and Stable Organic Photo-Sensitizers based on Triphenylamine with Multi-anchoring Chromophore for Dye-sensitized Solar Cells (트리페닐아민을 이용한 염료감응형 태양전지 고효율 염료합성)

  • Yang, Hyunsik;Jung, Daeyoung;Jung, Miran;Kim, Jaehong
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.88.1-88.1
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    • 2010
  • Organic dyes, because of their many advantages, such as high molar extinction coefficients, convenience of customized molecular design for desired photophysical and photochemical properties, inexpensiveness with no transition metals contained, and environment-friendliness, are suitable as photosensitizers for the Dye-sensitized Solar Cell (DSSC). The efficiency of DSSC based on metal-free organic dyes is known to be much lower than that of Ru dyes generally, but a high solar energy-to-electricity conversion efficiency of up to 8% in full sunlight has been achieved by Ito et al. using an indoline dye. This result suggests that smartly designed and synthesized metal-free organic dyes are also highly competitive candidates for photosensitizers of DSSCs with their advantages mentioned above. Recently, the performance of DSSC based on metal-free organic dyes has been remarkably improved by several groups. We had reported the novel organic dye with double electron acceptor chromophore, which was a new strategy to design an efficient photosensitizer for DSSC. To verify the strategy, we synthesized organic dyes whose geometries, electronic structures and optical properties were derived from preceding density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations. In this paper, we successfully synthesized the chromophore containing multi-acceptor push-pull system from triphenylamine with thiophene moieties as a bridge unit. Organic dyes with a single electron acceptor and double acceptor system were also synthesized for comparison purposes. The photovoltaic performances of these dyes were compared, and the recombination dark current curves and the incident photon-to-current (IPCE) efficiencies were also measured in order to characterize the effects of the multi-anchoring groups on the open-circuit voltage and the short-circuit current. In order to match specifications required for practical applications to be implemented outdoors, light soaking and thermal stability tests of these DSSCs, performed under $100mWcm^{-2}$ and $60^{\circ}C$ for 1000h.

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Methods to Improve Light Harvesting Efficiency in Dye-Sensitized Solar Cells

  • Park, Nam-Gyu
    • Journal of Electrochemical Science and Technology
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    • v.1 no.2
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    • pp.69-74
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    • 2010
  • Methodologies to improve photovoltaic performance of dye-sensitized solar cell (DSSC) are reviewed. DSSC is usually composed of a dye-adsorbed $TiO_2$ photoanode, a tri-iodide/iodide redox electrolyte and a Pt counter electrode. Among the photovoltaic parameters of short-circuit photocurrent density, open-circuit voltage and fill factor, short-circuit photocurrent density is the collective measure of light harvesting, charge separation and charge collection efficiencies. Internal quantum efficiency is known to reach almost 100%, which indicates that charge separation occurs without loss by recombination. Thus, light harvesting efficiency plays an important role in improvement of photocurrent. In this paper, technologies to improve light harvesting efficiency, including surface area improvement by nano-dispersion, size-dependent light scattering efficiency, bi-functional nano material, panchromatic absorption by selective positioning of three different dyes and transparent conductive oxide (TCO)-less DSSC, are introduced.

Synthesis and Photovoltaic Properties of Organic Photosensitizers for Application of Dye Sensitized Solar Cells (페노시아진을 이용한 염료감응형 태양전지 고효율 염료합성)

  • Yang, Hyun Sik;Shin, So Yeon;Kim, Yeun Ji;Kim, Jae Hong
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.119.2-119.2
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    • 2011
  • Dye-sensitized solar cells (DSSC) are currently attracting wide spread academic and commercial interest for the conversion of sunlight into electricity because of their easy manufacturing process and high efficiency. The solar energy conversion efficiencies of DSSC are strongly dependent on dye molecules adsorbed on the TiO2 surface which used for photosensitization of sun light, since an excited state of dye could inject an electron into the conduction band of semiconductor. We have developed novel organic dyes which have phenothiazine moieties as an electron donor in their charge-transfer chromophore for application of DSSCs. We had synthesized a series of phenothiazine derivatives which have different wave length absorbing chromophore in the molecule with high molar extinction coefficient. The photovoltaic performance of DSSC composed of organic chromophores with broad wavelength absorption property were measured and evaluated by comparison with that of pristine ruthenium dye.

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Dye-sensitized Solar Cells Based on Fluoran Leuco Sensitizers (플루오란 로이코 염료를 이용한 염료감응형 태양전지)

  • Jung, Hye-In;An, Byeong-Kwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.26 no.3
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    • pp.240-245
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    • 2013
  • The utilization of a fluoran leuco sensitizer, 2-anilino-6-dibutyl amino-3-methylfluoran (ODB-2), for dye-sensitized solar cells (DSSCs) was investigated through the examination of the adsorption of ODB-2 molecules onto the surfaces of porous titanium dioxide (titania, $TiO_2$) films and the photovoltaic properties of ODB-2-based DSSCs. Despite of the absence of the specific anchoring groups with titania, ODB-2 dye molecules were spontaneously adsorbed onto the titania surfaces because the lactone ring in ODB-2 was opened and changed into the carboxylic acid (-COOH) by releasing protons from the surfaces ($TiOH_2{^+}$) of titania, which consequently leads to the chemisorption reaction of ODB-2 molecules to the active sites of titania. DSSCs based on ODB-2 exhibited typical photovoltaic properties with an open-circuit voltage ($V_{OC}$) of 0.19 V, a short-circuit current ($J_{SC}$) of $0.30\;mA{\cdot}cm^{-2}$, a fill factor (FF) of 37%, and a conversion efficiency (PCE) of 0.02%.

Method to Increase the Surface Area of Titania Films and Its Effects on the Performance of Dye-Sensitized Solar Cells

  • Ko, Young-Seon;Kim, Min-Hye;Kwon, Young-Uk
    • Bulletin of the Korean Chemical Society
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    • v.29 no.2
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    • pp.463-466
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    • 2008
  • We report a method to increase the surface area of the titania films used as the anodes of dye-sensitized solar cells (DSSCs) by applying additional titania-coating. The modification was achieved by spin-coating a coating solution that contained a surfactant with a titania source onto the titania electrodes, followed by calcination. Previous similar attempts without a surfactant all reported decreased surface areas. We fabricated DSSCs by using the modified titania films as the anode and measured their performances. The increased surface area increased the amount of adsorbed dyes, which resulted in increased current densities. At the same time, the titania-coating increased both the open-circuit voltage and the current density by reducing the charge-recombination rates of the injected electrons, similar to the results of literatures. Therefore, our method shows an additional mechanism to increase the current density of DSSCs in addition to the other mechanisms of surface modifications with titania-coatings.

Solid State Dye-Sensitized Solar Cells Employing Polymer Electrolytes : Oligomer Approach

  • Kang, Yong-Soo;Lee, Yong-Gun;Kang, Moon-Sung;Kim, Jong-Hak;Char, Kook-Choen
    • Proceedings of the Polymer Society of Korea Conference
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    • 2006.10a
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    • pp.63-64
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    • 2006
  • The solid state dye-sensitized solar cells (DSSCs) employing polymer electrolytes show high overall energy conversion efficiency as high as 4.5 % at 1 sun conditions. The improved efficiency may be primarily due to the enlarged interfacial contact area between the electrolyte and dyes in addition to the increased ionic conductivity, which were done by utilizing liquid oligomers, followed by in situ self-solidification, to form the solid DSSCs: "Oligomer Approach". The effect of the charge transfer resistance at the counter electrode side on the efficiency has also been investigated.

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Adsorption Kinetic Study of Ruthenium Complex Dyes onto TiO2 Anodes for Dye-sensitized Solar Cells (DSSCs) (염료감응 태양전지용 루테늄 금속착체 염료의 이산화티타늄 전극에 대한 동적 흡착 연구)

  • An, Byeong-Kwan
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.11
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    • pp.929-934
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    • 2011
  • The adsorption kinetic study of ruthenium complex, N3, onto nanoporous titanium dioxide ($TiO_2$) photoanodes has been carried out by measuring dye uptake in-situ. Three simplified kinetic models including a pseudo first-order equation, pseudo second-order equation and intraparticle diffusion equation were chosen to follow the adsorption process. Kinetic parameters, rate constant, equilibrium adsorption capacities and related coefficient coefficients for each kinetic model were calculated and discussed. It was shown that the adsorption kinetics of N3 dye molecules onto porous $TiO_2$ obeys pseudo second-order kinetics with chemisorption being the rate determining step. Additionally the heterogeneous surface and the pore size distribution of porous $TiO_2$ adsorbents were also discussed.

Photocurrent and Its Stability Enhancement of Dye-sensitized Nanoparticle $TiO_2$ Solar Cells (염료감응 나노입자 $TiO_2$ 태양전지의 광전류와 그 안정성 향상)

  • Chae Won-Weok;Kang Tae-Sik;Kim Kang-Jin
    • Journal of the Korean Electrochemical Society
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    • v.2 no.4
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    • pp.232-236
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    • 1999
  • A solar cell based on dye-sensitized photoelectric conversion was studied by electrochemical and spec-trofluorometric methods for the purposes of enhancing its efficiency and stability of $TiO_2$ solar cells. Nanocrystalline $TiO_2$ was used to prepare photoelectrodes, and photosensitizing dyes such as malachite green oxalate, basic blue3, rhodamine B, and bromocresol purple were chosen as sensitizers. Electrochemical oxidation potentials and absorption and emission wavelengths of dyes were used to determine energy levels of the dyes. By comparing excited energy levels of the dyes with the conduction band edge potential $(E_{c,s})\;of\;TiO_2$ calculated by using the flat-band potential $(E_{fb})\;of\;TiO_2$, properties of a dye required to fabricate a high efficient photosensitizing solar cell with high short-circuit current $(J_{sc})$ were suggested. Enhanced stability of photocurrent was obtained by coating a $TiO_2|ITO$ electrode with Polypyrrole that Possibly Prevented the recombination between the conduction band electrons and oxidized dyes and suppressed the direct electrode redox reactions of dyes on ITO.

Efficiency Variation of Dye-Sensitized Solar Cell Influenced by Phosphor Additives (형광체 첨가에 따른 염료감응형 태양전지의 효율 변화)

  • Jung, Sung-Hoon;Hwang, Kyung-Jun;Kang, Sung-Won;Jeong, Hyung-Gon;Kim, Sun-Il;Lee, Jae-Wook
    • Applied Chemistry for Engineering
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    • v.20 no.2
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    • pp.227-233
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    • 2009
  • Recently, dye-sensitized solar cell (DSSC), one of the solar cells, has been widely investigated. Studies on DSSCs can be classified into 4 fields such as $TiO_2$ nanocrystalline materials, dyes, electrolytes and conductive plate. In this work, $TiO_2$ nanoparticles for dye adsorption were synthesized, and added into the photo-electrode paste with different phosphor types and contents. Then, the influence of phosphor additives on the conversion efficiency of DSSCs was investigated. It was found that the maximum conversion efficiency was 8.81% when 0.5% of YAG phospher having the particle size of 400 nm was used.