Celle solari di terza generazione (a fotosintesi )

Transcription

1 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).

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3 Dye sensitized solar cell

4 Dye sensitized solar cell Elettrolita e mediatore catodo Anodo o controelettrodo

5 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.

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7 Dye sensitized solar cell

8 Nanocrystalline TiO2

9 Nano-TiO2 Titania Synthesis by Ti Alkoxide and nonionic surfactant g of Titanium tetra isoproproxide 5 g of polyoxyethylene(18) tridecyl ether 10 ml of water Chemicals Titanium Tetraisoproproxide polyoxyethylene(18) tridecyl ether, 60 C C 13 EO 18

10 Mesoporous titania synthesis : TiO 2 from Ti alkoxide 300 ºC for 6 hours 350 ºC for 1 hour FE-SEM images of titanium oxide powder after calcination.

11 Mesoporous titania synthesis XRD and FTIR patterns of titanium oxide powders calcined at different temperatures.

12 Mesoporous titania synthesis FE-SEM images of titanium oxide powder after calcination at 350 ºC for 120 hours.

13 Mesoporous titania synthesis FE-SEM images of titanium oxide powder after calcination at 450 ºC for 6 hours.

14 Mesoporous titania synthesis (TiO 2 from titanatrane complex) TEM images of titanium oxide powder after calcination at 450 ºC for 6 hours.

15 Preliminary investigation of Dye-sensitized solar cell Titania gel Scotch tape Sintering 400 o C for 2 h Titanium plate Pt Doctor blading SnO 2 /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/cm 2 Cell size : 0.5 cm x 0.5 cm

16 Preliminary investigation of Dye-sensitized solar cell Current Density (ma/cm 2 ) Voltage (V) Jsc 8.83 ma/cm 2 Voc 0.73 V Power output 4.85 mw Vmax 0.6 V Jmax 8.09 ma FF 0.75 Efficiency 4.85

17 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)

18 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

19 Organic Solar Cells Organic solar cells: (a) single crystal heterojunction and (b) conjugated polymer/fullerene plastic solar cell.

20 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 the device is exciton diffusion limited. 2004_JMaterRes_(H Hoppe)

21 Energy Levels and Light Harvesting 2004_SolEngMat_(H Spanggaard)

22 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)

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24 Conjugated polymer solar cells

25 Eterogiunzioni

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27 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.

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29 Polymer solar cells

30 Quantum dots (QD) solar cells e nuovi concetti

31 Quantum Dot Tunable Bandgap

32 Quantum Dot Versatile in Form Colloidal synthesis Low processing temperature

33 Quantum Dots Stability and Lifetime Protective shell to increase stability

34 banda di conduzione banda intermedia (quantum dots) banda di valenza

35 QD-sensitized TiO 2 Solar Cell 2002_PhysicaE_(A Nozik)

36 QD / Polymer Solar Cell 2002_PhysicaE_(A Nozik)