Celle solari di terza generazione (a “fotosintesi”)

Celle solari di terza generazione
(a “fotosintesi”)
Esempi: photoelectrochemical cells, polymer solar cells (quarta
generazione), nanocrystal solar cells (a quantum dots), Dye-sensitized solar
cells
Celle fotovoltaiche a film sottile nanocristallino “dye sensitized solar cell”.
Il loro principio di funzionamento è diverso dalle comuni celle fotovoltaiche: si basa
sullo stesso meccanismo della fotosintesi clorofilliana.
Il ruolo della clorofilla è svolto da complessi organici di metalli transizione quali
Osmio e Rutenio. Questi assorbono la luce incidente e con l’energia raccolta
eccitano i loro elettroni.
Il ruolo della membrana lipidica è svolto da una membrana ceramica diossido di
titanio (TiO2).
Dye sensitized solar cell
Dye sensitized solar cell
Elettrolita e mediatore
catodo
Anodo o controelettrodo
Photocurrent action spectra obtained using simulated sunlight (AM 1.5) in above type of dye-sensitized solar
cells using three representative Ru-polypyridyl complexes: [(CN)(bpy)2Ru-CN-Ru(dcbpy)2-NCRu(bpy)2],
[Ru(4,4-bis(carboxy)-bpy)2(NCS)2] and [Ru(2,2',2"-(COOH)3-terpy)(NCS)3]. Plotted on the left is incident
photon-to-current conversion efficiency (IPCE) as a function of the excitation wavelength (for monochromatic
excitation). The IPCE value is the ratio of the observed photocurrent divided by the incident photon flux,
uncorrected for reflective losses for optical excitation through the conducting glass electrode.
Dye sensitized solar cell
Nanocrystalline TiO2
Nano-TiO2
Titania Synthesis by Ti Alkoxide and
nonionic surfactant
10.83 g of Titanium
tetra isoproproxide
5 g of polyoxyethylene(18)
tridecyl ether
10 ml
of
water
Chemicals
•
Titanium Tetraisoproproxide
•
polyoxyethylene(18) tridecyl ether,
C13EO18
60 ° C
Mesoporous titania synthesis : TiO2 from Ti alkoxide
300 ºC for 6 hours
350 ºC for 1 hour
FE-SEM images of titanium oxide powder after calcination.
Mesoporous titania synthesis
XRD and FTIR patterns of titanium oxide powders calcined at different temperatures.
Mesoporous titania synthesis
FE-SEM images of titanium oxide powder after calcination at 350 ºC for 120 hours.
Mesoporous titania synthesis
FE-SEM images of titanium oxide powder after calcination at 450 ºC for 6 hours.
Mesoporous titania synthesis (TiO2 from titanatrane complex)
TEM images of titanium oxide powder after calcination at 450 ºC for 6 hours.
Preliminary investigation of Dye-sensitized solar cell
Scotch tape
Sintering
Titanium plate
400oC for 2 h
Titania gel
Pt
Doctor blading
SnO2/ITO
Ruthenium dye solution (N719)
bis(tetrabutylammonium) cis di(thiocyanato)
bis(2,2’-bipyridine-4,4’-carboxylic acid) Ruthenium (II)
I-V characteristic :
Simulated sun light (CEP2000)：
- AM 1.5，100 mW/cm2
Cell size : 0.5 cm x 0.5 cm
Preliminary investigation of Dye-sensitized solar cell
Jsc
Voc
Power output
Vmax
Jmax
FF
Efficiency
10.00
2
Current Density (mA/cm)
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
0
0.1
0.2
0.3
0.4
0.5
Voltage (V)
0.6
0.7
0.8
0.9
8.83 mA/cm2
0.73 V
4.85 mW
0.6 V
8.09 mA
0.75
4.85
Nanocristalline ZnO
SEM images of ZnO nanowires (Inset in (d) shows transmission electron diffraction
pattern obtained from a nanowire with many secondary nanowires emanating from
its surface. Scale bar is 5 mm in (a) and (c) and 200nm in (b) and (d)
Excitonic Solar Cells
There are three prototypes of these solar cells: dye sensitized
nanocrystalline thin film (Gratzel solar cell), organic polymer, and
nanoparticle/organic polymer composite
Organic Solar Cells
Organic solar cells: (a) single crystal heterojunction and
(b) conjugated polymer/fullerene
‘‘plastic solar cell’’.
Single Layer Organic Solar Cell
Schematic of a single layer device with a Schottky contact at the aluminum contact.
Photogenerated excitons can only be dissociated in a thin depletion layer W, and thus
2004_JMaterRes_(H Hoppe)
the device is exciton diffusion limited.
Energy Levels and Light
Harvesting
2004_SolEngMat_(H Spanggaard)
Heterojunction Organic Solar
Cells
Exciton dissociation at the donor–acceptor
interface. The electron goes to the acceptor
while the hole stays on the donor.
A two-layer heterojunction photovoltaic cell. The
electron accepting C60-layer contacts the Au
electrode, while the electron donating MEH-PPV
layer contacts the ITO electrode.
2004_SolEngMat_(H Spanggaard)
Conjugated polymer solar cells
Eterogiunzioni
2004_SolEngMat_(H Spanggaard)
Different morphologies of heterojunction cells. Top, left: Two-layered structure of fullerenes and
polymer chains. Top, right: dispersed heterojunction. Middle, left: fullerenes with polymer chains
attached. Middle, right: self-assembled layered structure of double-cable polymers. Bottom: selfassembled layered structure of diblock copolymers. The layered structure of double-cable polymers
and diblock
copolymers are expected to facilitate efficient electron and hole transport.
Polymer solar cells
Quantum dots (QD) solar cells
e nuovi concetti
Quantum Dot – Tunable
Bandgap
Quantum Dot – Versatile in
Form
• Colloidal synthesis
• Low processing temperature
Quantum Dots – Stability and
Lifetime
• Protective shell to increase stability
banda di conduzione
banda intermedia
(quantum dots)
banda di valenza
QD-sensitized TiO2 Solar Cell
2002_PhysicaE_(A Nozik)
QD / Polymer Solar Cell
2002_PhysicaE_(A Nozik)