Thiophene-fused coplanar sensitizer for dye-sensitized solar cells

We have designed and synthesized a novel ladder-type heteroacene dye consisting uniquely of thiophene segments as a photosensitizer for the dye-sensitized solar cells (DSSCs). The onset of the IPCE spectrum for the dye not only reaches up to 700 nm with a high IPCE (>60%) but also a solar energy-to-electricity conversion efficiency of 2.31% is achieved. Even though the efficiency is slightly lower than those of other dyes reported previously, this work opens up a new strategy to design heteroaromatic fused photosensitizers for DSSCs.     

A highly efficient organic sensitizer for dye-sensitized solar cells

We have synthesized a highly efficient organic dye for a dye-sensitized solar cell; the overall solar-to-energy conversion efficiency was 9.1% at AM 1.5 illumination (100 mW cm(-2)): short-circuit current density (J(sc)) = 18.1 mA cm(-2), open circuit photovoltage (V(oc)) = 743 mV and fill factor (ff) = 0.675.     

A high molar extinction coefficient sensitizer for stable dye-sensitized solar cells

An amphiphilic heteroleptic polypyridyl ruthenium complex with a high molar extinction coefficient was synthesized and demonstrated as an efficient, thermostable sensitizer in nanocrystalline dye-sensitized solar cells.     

Efficient and stable panchromatic squaraine dyes for dye-sensitized solar cells

A new series of stable, unsymmetrical squaraine near-IR sensitizers (JK-216 and JK-217), which are assembled using both thiophenyl pyrrolyl and indolium groups, exhibit a panchromatic light harvesting up to 780 nm. The JK-216 based cell exhibited a record efficiency of 6.29% for near-IR DSSCs. In addition, the JK-217 device showed an excellent stability under a light soaking test at 60 °C for 1000 h.     

A novel metal-free panchromatic TiO2 sensitizer based on a phenylenevinylene-conjugated unit and an indoline derivative for highly efficient dye-sensitized solar cells

A novel donor-π-spacer-acceptor type organic dye (AK01) bearing a phenylenevinylene-conjugated system and a derivative of indoline donor was synthesized for dye-sensitized solar cells. AK01 showed panchromatic TiO(2) sensitization with high overall conversion efficiency of 6.2% under AM 1.5 illumination (100 mW cm(-2)).     

Unsymmetrical squaraines incorporating the thiophene unit for panchromatic dye-sensitized solar cells

Two unsymmetrical squaraines, where the electron-rich 3,4-ethylenedioxythiophene or bithiophene conjugated fragment was used to link unconventionally the squaraine core and the hexyloxyphenyl amino group, were applied for DSCs. The corresponding photovoltaic devices exhibit an attractively panchromatic response and also convert a portion of the near-infrared photons into electricity.     

Panchromatic trichromophoric sensitizer for dye-sensitized solar cells using antenna effect

The first trichromophoric sensitizer, consisting of covalently linked boradiazaindacene (BODIPY), zinc porphyrin (ZnP), and squaraine (SQ) units, has been synthesized by Heck alkynylation to obtain a panchromatic dye, for dye sensitized solar cells (DSSCs). Efficient intramolecular energy transfers (ET) were observed between all chromophoric subunits and enhance the overall conversion efficiency by 25%. The antenna effect is demonstrated by the photoaction spectrum which features all of a chromophore's absorption bands.     

Electron-rich heteroaromatic conjugated bipyridine based ruthenium sensitizer for efficient dye-sensitized solar cells

A novel heteroleptic ruthenium complex carrying a heteroaromatic-4,4'-pi-conjugated 2,2'-bipyridine [Ru(II)LL'(NCS)(2)] (L = 4,4'-bis[(E)-2-(3,4-ethylenedioxythien-2-yl)vinyl]-2,2'-bipyridine, L' = 4,4'-(dicarboxylic acid)-2,2'-bipyridine) was synthesized and used in dye-sensitized solar cells, yielding photovoltaic efficiencies of 9.1% under standard global AM 1.5 sunlight.     

Cyclometalated ruthenium complex as a promising sensitizer in dye-sensitized solar cells

Ruthenocycle bis(4,4′-dicarboxy-2,2′-bipyridine)(2-phenylpyridine-²C,N)ruthenium(II) hexafluorophosphate was used as a sensitizer in a dye-sensitized solar cell (DSSC) based on nanocrystalline TiO₂, which was applied onto a conducting substrate. Its electrochemical and spectral characteristics were studied. It was found that, when the DSSC was illuminated with visible light of power 35 mW/cm², the short-circuit current density was 11.6 mA cm^?2 and the open-circuit voltage was 0.49 V. The efficiency (η) of DSSC at a fill factor of 45% was 7.1%. Using the method of modulation spectroscopy of photocurrents and photopotentials, the life time and transit time of electrons were found to be 7 and 5 ms, respectively, and the diffusion coefficient of electrons was found to be 10^?5 cm² s^?1. Comparing the life and transit times of electron, it was concluded that the photogenerated electrons had time to reach the conducting substrate during their life time.     

Effect of sensitizer adsorption temperature on the performance of dye-sensitized solar cells

Employing a mesoscopic titania photoanode whose bilayer structure was judiciously selected to fit the optoelectronic characteristics of the Ru-based heteroleptic complex Na-cis-Ru(4,4'-(5-hexyltiophen-2-yl)-2,2'-bipyridine)(4-carboxylic-acid-4'-carboxylate-2,2'-bipyridine)(thiocyanate)(2), coded as C101, we investigated the effect of temperature for dye adsorption on the photovoltaic performance of dye-sensitized solar cells (DSCs). We found a significant efficiency enhancement upon lowering the temperature applied during the sensitizer uptake from solution. When the dye adsorption was performed at 4 °C, the photovoltaic performance parameters measured under standard reporting conditions (AM1.5 G sunlight at 1000 W/m(2) intensity and 25 °C), i.e., the open circuit voltage (V(oc)), the short circuit photocurrent density (J(sc)), the fill factor (FF), and consequently the power conversion efficiency (PCE), improved in comparison to cells stained at 20 and 60 °C. Results from electrochemical impedance spectroscopy (EIS) and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) show that the self-assembled layer of C101 formed at lower temperature impairs the back-electron transfer from the TiO(2) conduction band to the triiodide ions in the electrolyte more strongly than the film produced at 60 °C. Profiting from the favorable influence that the low-temperature dye uptake exerts on photovoltaic performance, we have realized DSCs showing a power conversion efficiency of 11.5%.     

A new 1H-pyridin-(2E)-ylidene ruthenium complex as sensitizer for a dye-sensitized solar cell

The new heteroleptic ruthenium(II) complex containing a 1H-pyridin-(2E)-ylidene (PYE) ligand was synthesized and characterized using UV/Vis, FTIR, and NMR spectroscopies, mass spectrometry, elemental analysis, and cyclic voltammetry. The photovoltaic performance of the ruthenium complex as a charge transfer photosensitizer in nc-titanium dioxide based dye-sensitized solar cell was studied and compared with cis-bis(isothiocyanato)(2,2′-bipyridyl-4,4′-dicarboxylato)(2,2′-bipyridyl-4,4′-di-nonyl)ruthenium(II) (Z907) under standard AM 1.5 sunlight. The complex CS90 gave a photocurrent density of 1.80?mA?cm^?2, 400?mV open-circuit potential, and 0.58 fill factor yielding an efficiency of 0.42% where the reference Z907 yielded an efficiency of 4.12%. The decrease in conversion efficiency observed for CS90 is attributed to a steric interaction between PYE and the TiO₂ surface that prevents optimum binding and also restricts ligand dynamics that are associated with oxidation state changes.     

Synthesis of new di-anchoring organic sensitizer based on quinoxaline acceptor for dye-sensitized solar cells

New quinoxaline-based organic sensitizer bearing di-anchoring group for dye-sensitized solar cells (DSSCs) was synthesized from diethyl 4,5-diaminophthaltate, in which was prepared under mild condition by using Takehito’s method. The synthesized sensitizer was compared with mono-anchoring sensitizer through absorption spectra, emission spectra, J-V curve, and IPCE spectra, indicating the di-anchoring group leads to a noticeable improvement of J_sc value owing to more efficient intramolecular charge transfer and channel number increment.     

Efficient thiocyanate-free sensitizer: a viable alternative to N719 dye for dye-sensitized solar cells

We have designed and synthesized a new thiocyanate-free sensitizer coded as SPS-01 and used it as the sensitizer in a TiO(2) based nanocrystalline dye-sensitized solar cell (DSSC). SPS-01 exhibits strong visible absorption properties with maximum peak around at 532 nm. The overall power conversion efficiency (PCE) of a DSSC sensitized with SPS-01 (7.96%) is higher than that of N719 (7.30%) under identical experimental conditions. This high PCE is attributed mainly due to the improvement in the short circuit current.     

Synthesis of a novel unsymmetrical Zn(II) phthalocyanine bearing a phenyl ethynyl moiety as sensitizer for dye-sensitized solar cells

A new unsymmetrical zinc phthalocyanine sensitizer has been synthesised. The anchoring of the molecule to nanocrystalline TiO(2) films is realised by a carboxylic group connected to a phenyl ethynyl moiety. Density Functional Theory (DFT) calculations show significant and positive effects of such a functionalization. Electron injection into the semiconductor and photocurrent generation in DSSC are also presented.     

An organic sensitizer with a fused dithienothiophene unit for efficient and stable dye-sensitized solar cells

We report a high molar extinction coefficient organic sensitizer for high efficiency dye-sensitized solar cells. In combination with a solvent-free ionic liquid electrolyte, we have demonstrated a approximately 7% cell showing an excellent stability measured under the thermal and light soaking dual stress. This is expected to have an important practical consequence on the production of flexible, low-cost, and lightweight DSC based on plastic matrix.     

N-methylferrocenyl-N-ethylhydroxy ammonium nitrate: synthesis,characterization, and sensitizer in dye-sensitized solar cells

Transition Metal Chemistry - A new ferrocene-containing hydronitrate salt with formula N-methylferrocenyl-N-ethylhydroxy ammonium nitrate has been synthesized and characterized using microanalyses,...     

A fluorene-modified porphyrin for efficient dye-sensitized solar cells

Porphyrins bearing a polyaromatic or a heterocyclic group are prepared to study their fundamental and photovoltaic properties. Solar cells sensitized with a fluorene-modified porphyrin outperform other dyes in the series, reaching ~90% efficiency of N719 dye.