Molecular Adjustment of the Electronic Properties of Nanoporous Electrodes in Dye-Sensitized Solar Cells

Rühle, Sven; Greenshtein, Miri; Chen, S.-G.; Merson, Alexandra; Pizem, Hillel; Sukenik, Chaim S.; Cahen, David; Zaban, Arie

doi:10.1021/jp0514123

Cited by 329 publications

(232 citation statements)

References 32 publications

(49 reference statements)

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“…22 On the other hand, the area occupied by N3 molecules at full monolayer coverage was found to be 1.65 nm 2 due to its larger molecular size. 10 Note that a monolayer coverage of a particular type of modifiers does not necessary mean perfect coverage, as additional coadsorption of smaller molecules 45 and intercalation of solvent molecules can be possible.…”

Section: Resultsmentioning

confidence: 99%

Effects of molecular interface modification in hybrid organic-inorganic photovoltaic cells

Goh¹,

Scully²,

McGehee³

2007

Journal of Applied Physics

443

457

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We have systematically investigated the effects of surface modification of titania (TiO 2 ) in hybrid TiO 2 /regioregular poly(3-hexylthiophene) (P3HT) photovoltaic cells.By employing a series of para-substituted benzoic acids with varying dipoles and a series of multiply-substituted benzene carboxylic acids, the energy offset at the TiO 2 /polymer interface and thus the open circuit voltage of devices can be tuned systematically by 0.25 V. Transient photovoltage measurements showed that the recombination kinetics were dominated by charge carrier concentration in these devices and were closely associated with the dark current. The saturated photocurrent of TiO 2 /P3HT devices exhibits more than a two-fold enhancement when molecular modifiers with large electron affinity were employed. The ability of modifiers to accept charge from polymers, as revealed in photoluminescence quenching measurement with blends of polymers, was shown to be correlated to the enhancement in device photocurrent.A planar geometry photoluminescence quenching measurement showed that TiO 2 substrates modified by these same molecules that accept charge quenched more excitons in regioregular P3HT than bare TiO 2 surfaces. An exciton diffusion length in P3HT as large as 6.5 -8.5 nm it was found that all of the excitons that were quenched were accountable as extracted photocurrent. EQE was effectively increased from 5% to 10 -14% with certain surface modifiers; consequently exciton harvesting was more than doubled. The use of Ruthenium (II) sensitizing dyes with good exciton harvesting property coupled with suppression of the recombination kinetics improved the efficiency of optimized bilayer TiO 2 /P3HT devices from 0.34 % to 0.6 % under AM 1.5 solar illuminations. The implication of this work is directly relevant to the design of nanostructured bulk heterojunction inorganic-organic cells, in which efficient exciton harvesting and control of the recombination kinetics are key to achieving high efficiency. _____________________________ a) Electronic

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Section: Resultsmentioning

confidence: 99%

Effects of molecular interface modification in hybrid organic-inorganic photovoltaic cells

Goh¹,

Scully²,

McGehee³

2007

Journal of Applied Physics

443

457

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“…3 and discussed later. 39 Besides shifting the conduction band of the semiconductor, adsorbed molecules also are able to reduce recombination and increase the efficiency of DSC. 40,41 Finally some architectures require the combination of different elements with specific photophysical, physical or electrochemical functions.…”

Section: Nanoparticles and Nanostructuresmentioning

confidence: 99%

Physical electrochemistry of nanostructured devices

Bisquert

2008

Phys. Chem. Chem. Phys.

243

273

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“…The semiconductor conduction band shift (with respect to the electrolyte redox potential, Dc) can be expressed as a function of the dipole moment of adsorbed dye [Eq. (7)]: [58] Dc ¼ À qm normal g e 0 e ð7Þ where q is the majority carrier charge (AE 1.6 10 À19 C), g measures the dye's surface concentration (10 17 to 10 18 m 2 ), and m normal is the component of the dipole moment of the individual molecule perpendicular to the semiconductor surface (usually 1-50 Debye; the positive direction is defined as the dipole moment pointing toward the TiO 2 film). e and e 0 are the dielectric constant of the monolayer and the permittivity of the vacuum, respectively.…”

Section: Tpa Dyes On Tio 2 Surfacesmentioning

confidence: 99%

Acene‐Modified Triphenylamine Dyes for Dye‐Sensitized Solar Cells: A Computational Study

2012

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A series of metal‐free acene‐modified triphenylamine dyes (benzene to pentacene, denoted as TPA‐AC1 to TPA‐AC5) are investigated as organic sensitizers for application in dye‐sensitized solar cells (DSSCs). A combination of density functional theory (DFT), density functional tight‐binding (DFTB), and time‐dependent DFT (TDDFT) approaches is employed. The effects of acene units on the spectra and electrochemical properties of the acene‐modified TPA organic dyes are demonstrated. The dye/(TiO2)46 anatase nanoparticle systems are also simulated to show the electronic structures at the interface. The results show that from TPA‐AC1 to TPA‐AC5 with increasing sizes of the acenes, the absorption and fluorescence spectra are systematically broadened and red‐shifted, but the oscillator strength and electron injection properties are reduced. The molecular orbital contributions show increasing localization on the bridging acene units from TPA‐AC1 to TPA‐AC5. From the theoretical examination of some key parameters including free enthalpy related to the electron injection, light‐harvesting efficiency, and the shift of semiconductor conduction band, TPA‐AC3 with an anthracene moiety demonstrates a balance of the above crucial factors. TPA‐AC3 is expected to be a promising dye with desirable energetic and spectroscopic parameters in the DSSC field, which is consistent with recent experimental work. This study is expected to deepen our understanding of TPA‐based organic dyes and assist the molecular design of new metal‐free dyes for the further optimization of DSSCs.

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Molecular Adjustment of the Electronic Properties of Nanoporous Electrodes in Dye-Sensitized Solar Cells

Cited by 329 publications

References 32 publications

Effects of molecular interface modification in hybrid organic-inorganic photovoltaic cells

Effects of molecular interface modification in hybrid organic-inorganic photovoltaic cells

Physical electrochemistry of nanostructured devices

Acene‐Modified Triphenylamine Dyes for Dye‐Sensitized Solar Cells: A Computational Study

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