Investigation of the minimum driving force for dye regeneration utilizing model squaraine dyes for dye-sensitized solar cells

Pradhan, Anusha; Morimoto, Takuya; Saikiran, Maryala; Kapil, Gaurav; Hayase, Shuzi; Pandey, Shyam S.

doi:10.1039/c7ta06990a

Cited by 21 publications

(10 citation statements)

References 46 publications

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“…CV of the dyes was performed in DCM solution containing 2 mM respective dyes and 0.1 M tetrabutylammonium perchlorate electrolyte at a scan rate of 100 mV s –1 . Optimized geometries of final dyes along with the HOMO, LUMO, and absorption spectra were calculated using TD-DFT without any symmetry restriction using linear spin density approximation as optimized functional for squaraine dyes and 6-311G basis set as executed in Gaussian 09 program package. − …”

Section: Methodsmentioning

confidence: 99%

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Synthesis and Optoelectrical Characterization of Novel Squaraine Dyes Derived from Benzothiophene and Benzofuran

et al. 2018

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Synthesis and photophysical characterizations of two novel small molecules SQ-BEN-THI and SQ-BEN-FUR with D–A–D molecular structure consisting of squaraine as central unit and benzothiophene and benzofuran as end groups are being reported. Apart from very sharp and intense light absorption by these molecular sensitizers in near-infrared (NIR) wavelength region, their possibility as small molecular organic semiconductor was also explored after fabricating organic field-effect transistors (OFETs). Results obtained from photophysical, electrochemical, and quantum chemical studies were combined to elucidate the structural and optoelectronic properties. Electrical characterization pertaining to the charge-transport properties carried after OFET fabrication exhibited field-effect mobilities of 4.0 × 10 –5 and 5.4 × 10 –5 cm 2 /(V s) for SQ-BEN-THI and SQ-BEN-FUR , respectively. After thermal annealing at 130 °C, the field-effect mobility was found to increase for both squaraine dyes. Relatively facile carrier transport in SQ-BEN-FUR compared to that of SQ-BEN-THI could be attributed to relatively higher backbone planarity as indicated from optimized molecular structure obtained after density functional theory calculations. This work may guide for further molecular design and synthesis of novel squaraine dyes for high-performance OFET applications.

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Section: Methodsmentioning

confidence: 99%

“…Optimized geometries of final dyes along with the HOMO, LUMO, and absorption spectra were calculated using TD-DFT without any symmetry restriction using linear spin density approximation as optimized functional for squaraine dyes and 6-311G basis set as executed in Gaussian 09 program package. 40−42…”

Section: Experimental Sectionmentioning

confidence: 99%

Synthesis and Optoelectrical Characterization of Novel Squaraine Dyes Derived from Benzothiophene and Benzofuran

et al. 2018

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“…In this manner, the optical activity of diradical croconate and squarate dyes has been extensively studied during the last decades due to the intense color and the narrow and strong band they present in the red to near‐infrared (NIR) region of the absorption spectra, so that they have become very popular in the photovoltaic field . For instance, in the design of dye‐sensitized solar cells with enhanced light harvesting capabilities in the NIR ,,. Such interest has motivated the detailed theoretical and experimental characterization of their singlet‐singlet transitions,,,, and it is well known that the presence of donor or acceptor moieties on the backbone, π‐conjugation,,,, or heavy atoms may lead to modifications in the absorption energy.…”

Section: Introductionmentioning

confidence: 99%

Potential Use of Squarates and Croconates as Singlet Fission Sensitizers

2018

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The geometrical and electronic structures of 44 squarate and croconate derivatives are computationally studied by quantum chemistry methods, in the pursuit of new singlet fission sensitizers. A non-negligible singlet open-shell diradical character is observed for most of the studied molecules, which can be controlled through chemical substitution as well as by the size of the central ring. Such a diradical character is related to small singlet-triplet energy gaps, facilitating the accomplishment of the singlet fission energetic requirements. In general, the present results indicate that squarates hold superior singlet fission capabilities than croconates, although we have identified several derivatives within both families as promising singlet fission sensitizers.

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“…Since cobalt-based redox electrolytes have a relatively deeper redox energy level as compared to commonly used iodine-based electrolytes, care must be taken for controlling the energetics of the newly designed dyes under investigation. Recently we have demonstrated the need for minimum driving force of 0.12 eV for the dye regeneration using far-red-sensitive model squaraine dyes and iodine-based redox electrolyte …”

Section: Introductionmentioning

confidence: 99%

“…Recently we have demonstrated the need for minimum driving force of 0.12 eV for the dye regeneration using far-red-sensitive model squaraine dyes and iodine-based redox electrolyte. 19 In this work, we report about the design of novel blue colored dyes possessing an intense and sharp light absorption along with photon harvesting mainly in the far-red region. Our design was based on the introduction of long alkyl chains in the dye molecular structure required to work with the cobaltbased redox shuttle.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Photophysical Characterization of Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells Utilizing Cobalt Electrolytes

Pradhan

Kiran

Kapil

et al. 2018

ACS Appl. Energy Mater.

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Development of novel near-infrared (near-IR) dyes compatible with cobalt complex based redox shuttles for their utilization as sensitizer is inevitable for the fabrication of high-efficiency dye-sensitized solar cells (DSSCs). A series of newly designed unsymmetrical squaraine dyes as a model of near-IR sensitizer were synthesized and characterized for their application as far-red sensitizers of DSSCs utilizing Co(bpy)2+/3+ redox electrolyte. It was shown that logical molecular design led to not only energetic tunability of the sensitizers but also the possibility of good far-red photon harvesting up to 750 nm. One of the newly designed sensitizers, SQ-110, bearing two long alkyl substituents in combination with an electron donating methoxy group directly linked to the aromatic ring was par excellent in terms of its photoconversion efficiency among the dyes utilized in this work. DSSC fabricated using SQ-110 as sensitizer and Co(bpy)2+/3+ redox electrolyte furnished a photoconversion efficiency of 1.98% along with good photon harvesting mainly in the far-red wavelength region. It was further demonstrated that dye molecular structure plays a rather more prominent role than their energetics in controlling the overall device performance of the DSSCs.

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Investigation of the minimum driving force for dye regeneration utilizing model squaraine dyes for dye-sensitized solar cells

Abstract: Combined theoretical and experimental approaches using model squaraine dyes as a representative of NIR sensitizers have demonstrated the possibility for facile dye regeneration, with a very small driving force of 0.12 eV, from the most commonly used iodine based redox electrolytes.

Cited by 21 publications

References 46 publications

Synthesis and Optoelectrical Characterization of Novel Squaraine Dyes Derived from Benzothiophene and Benzofuran

Synthesis and Optoelectrical Characterization of Novel Squaraine Dyes Derived from Benzothiophene and Benzofuran

Potential Use of Squarates and Croconates as Singlet Fission Sensitizers

Synthesis and Photophysical Characterization of Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells Utilizing Cobalt Electrolytes

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