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A review on Dye-Sensitized Solar Cells
Transcript of A review on Dye-Sensitized Solar Cells
Dye Sensitized Solar Cells
Ernesto Baena Murillo
Asignatura: “Semiconductores: Fundamentos y dispositivos”
Máster en Nanociencia y Nanotecnología Molecular
Universidad de Alicante - 2011
"Solar Cell" + Dye
1. Reduce desorption
2. Recombination inhibition
Different Metal Oxides as Semiconductor
Long Aliphatic Chains in the Sensitizer
High Molar Extinction
Lowest Metal-to-Ligand Charge transfer:
-400 nm: 35.000/M cm
-545 nm: 19.000/M cm
Intermediate design: HMECS + HS
Thickness of Semiconductor
-Ordered oxide mesostructures in SC.
-Control on the interfacial charge recombination dynamics
Where is the future?
-Extending light response to NIR.
Why insist in DSSC?
Excellent performance in diffuse light conditions.
Economically fertile field.
- Single Junction=10%
- Tandem Cells=15%
Prof. Grätzel: nanoporous films into dye-derived wideband semiconductor.
DSC's: High efficiency, Potential low-cost, Simple assemble.
Great scientific boom: First demonstration of 10% efficiency SC by Grätzel certified by NREL (National Renewable Energy Laboratory-U.S. Department of Energy).
Structure and Operating Principle
Semiconductor Film Electrode
Aims in 'i+R+D'
Carrier for the monolayers of the sensitizer using their high surface area
Medium of electron transfer to the conducting substrate
TiO2, ZnO, SnO2, Nb2O5...
Abundance in market and nature
How to... TiO2?
Colloidal TiO2 dispersions:
high energy milling
Light Scattering Particles
Lightweight & thickness!!
BUT: It is not possible to sinterize TiO2 on polymer substrates...
-Ti-metal foil for photoanode
-Pt-electrodeposited counterlectrode on ITO-PEN
Different band-gaps for the semiconductor:
Spacer Units between oxidized dye and SC
Surface pasivation of SC:
-metal oxides and insulating polymers.
-Increase FF and Voc
Absorb all light below 920 nm
Adsorb firmly on SC surface
Quantum Yield = 1
Certain RedOx potential: regenerate rapidly from the electrolyte.
100.000.000 RedOx Cycles: 20 years of exposure to natural light.
Metal complexes of Ru and Os.
High thermal and chemical stability
Natural and synthetic
Easily design of MEC
fast ion diffusion
easy to be designed
high pervasion into nanocrystalline film electrode
The composition of the electrolytes includes:
nitriles: as acetonitrile, valeronitrile, 3-methoxypropionitrile
esters: as ethylene carbonate (EC), propylene carbonate (PC)
Alkyl imidazolium cation (counter-ion) may be adsorbed on semiconductor to form a DL, which restricted the contact of I3- and semiconductor, so recombination is suppresed.
4-tert-butylpyridine (TBP) andN-methylbenzimidazole (NMBI).
Suppress the dark current and improve the photoelectric conversion efficiency.
TBP reduce the recombination through the coordination between N atom and the Ti ion in incomplete coordination state on the surface of TiO2 film.
less long-term stability
difficulty in robust sealing
leakage of electrolyte due to the volatility of organic solvent.
good chemical and thermal stability
negligible vapor pressure
high solubility for organic or inorganic materials
wide electrochemical window
Developed in recent years in view of the disadvantage of organic solvent electrolyte.
Viscosity is much higher than that of organic liquid electrolyte.
Then the transport I3− in the electrolyte is very slow.
To improve the mobility of redox couple in the electrolyte, various ionic liquid with low viscosity have been developed.
p-type semiconductor or hole transporting organic materials to replace a liquid electrolyte.
to improve the long-term stability
conversion efficiencies are not comparable with those of the liquid solar cells.
It can be seen that the module efficiency is still low for practical application.
More than 11% efficiency have achieved by EPFL and Sharp Corporation in small-area DSC.
Since 1993, industrial researchers have led the way with teams from Germany, Australia, and Switzerland. Based on licenses to the core patents held by EPFL
Sharp Corporation and Arakawa group reported 6.3% (efficient area: 26.5 cm2, confirmed, 6.3% for 101 cm2) and 8.4% (100 cm2) conversion efficiency for DSC modules.
Gifu University (Japan) developed colorful plastic solar cells with the efficiency of 5.6% based on organic indoline dye and electrodeposited nanocrystalline ZnO film electrode.
Toin University of Yokohama (Japan) has achieved more than 6%conversion efficiency on full flexible solar cells based on low-temperature TiO2 electrode preparation technology.
There are more than 30 groups engaged in the research of DSC. The research involved the dye sensitizers, nanocrystalline semiconductor film, electrolyte, counter electrode, substrate and theoretical research of interface transport, and so forth.
Later in the decade, electrophotochromic windows should be commercialized.
Replace of fossil fuels
Developing Countries (?)
High energy consumption for fabrication
Materials: toxic and low availability in nature (Cd, Te...)
Effiencies: long way behind "organics"
1) Light absorption
2) Exciton formation
3) Charge injection
4) Charge transport and extraction
Polypiridyl Complexes of Ruthenium
Long term stability
Inmobilization to substrates via ester linkages
Enhave VIS light absorption
Surface dipole due to proton transfer
Positive shift of conduction band edge
Inhibition of activity of polarized water molecules near S.C. substrate
"gel-like" network of aliphatic chains covering S.C. from electrolite
To improve the paradigm: red absorption
LUMO fine tuning
Solar Cell + Dye
In chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons
The developing countries should not inhibit the increase in energy consumption.
These are the countries with high consumption who must rethink their models.
Most cited topics for "Solar Cell"
thanks for your attention