Nanoscience in (Solar) Energy Research

Transcription

1 Nanoscience in (Solar) Energy Research Arie Zaban Department of Chemistry Bar-Ilan University Israel Nanoscience in energy conservation: TBP

2 10 TW - PV Land Area Requirements 10 TW 3 TW

3 10 TW Power Stations 1400 MW power plant (Hadera) One plant, each day, for the next: 19.5 years

4 Single-Bandgap Photovoltaics and the solar spectrum (AM 1.5) 4E+27 photons/(m 2 ev) 3E+27 2E+27 1E hν (ev)

5 Optimal Bandgap Prince, JAP 26 (1955) 534 Loferski, JAP 27 (1956) 777

6 Multi-Bandgap Photovoltaics and the solar spectrum (AM 1.5) 4E+27 photons/(m 2 ev) 3E+27 2E+27 1E hν (ev)

7 Multi-Bandgap Photovoltaics cost concentration current matching

8 Maximum Efficiency for an Ideal Multigap System With optical losses Bennett and Olsen, 1988, IEEE PVSC, p. 868

9 The Photovoltaic (PV) Mechanism

10 The Green Picture one electron energy contact e - Low energy state Absorber High energy state p + contact Metastable high and low energy state Absorber which transfers charges into the high and low energy states Driving force which brings the charges to the contacts Selective contacts No/slow recombination 1) Green, M.A., Photovoltaic principles. Physica E, : : p

11 Dye Sensitized Solar Cell (DSSC) TiO 2 Metastable high and low energy state red Absorber to transfer charges into the energy states ox Force driving charges to the contacts glass TCO (Transparent Conducting Oxide) semiconductor dye electrolyte Selective contacts No/slow recombination

12 Extremely Thin Absorber Cell (ETA) Metastable high and low energy state red Absorber to transfer charges into the energy states ox Force driving charges to the contacts glass TCO (Transparent Conducting Oxide) semiconductor SC electrolyte Selective contacts No/slow recombination

13 Solid State ETA Cell Metastable high and low energy state Absorber to transfer charges into the energy states Force driving charges to the contacts glass TCO (Transparent Conducting Oxide) semiconductor SC semiconductor Selective contacts No/slow recombination

14 Electrochemical Absorber Solar Cell Metastable high and low energy state Absorber to transfer charges into the energy states Force driving charges to the contacts glass TCO (Transparent Conducting Oxide) semiconductor electrolyte semiconductor Selective contacts No/slow recombination

15 Electrochemical Contacts Solar Cell red Metastable high and low energy state ox red Absorber to transfer charges into the energy states ox Force driving charges to the contacts glass TCO (Transparent Conducting Oxide) electrolyte SC electrolyte Selective contacts No/slow recombination

16 Why Nano? Dye Sensitized Solar Cell TiO 2 Surface area red ox Optical density vs. charge separation efficiency: Injection Exciton diffusion length Charge migration glass TCO (Transparent Conducting Oxide) semiconductor dye electrolyte Materials (quality, cost) Production

17 High Surface Area Electrode Conductive Substrate Conductive Substrate Conductive Substrate Conductive Substrate Conductive Substrate

18 TiO2 dye semiconductor Why Nano? Dye Sensitized Solar Cell red ox electrolyte dye ox red glass TCO (Transparent Conducting Oxide) conductive substrate

19 The Nanoporous Electrode Dye Sensitized Solar Cell Conductive Substrate

20 Single-Bandgap Photovoltaics and the solar spectrum (AM 1.5) 4E+27 photons/(m 2 ev) 3E+27 2E+27 1E hν (ev)

21 Optimal Bandgap Prince, JAP 26 (1955) 534 Loferski, JAP 27 (1956) 777

22 Multi-Bandgap Photovoltaics and the solar spectrum (AM 1.5) 4E+27 photons/(m 2 ev) 3E+27 2E+27 1E hν (ev)

23 Multi-Bandgap Photovoltaics cost concentration current matching

24 Up-Conversion for a Single Junction 4E+27 photons/(m 2 ev) 3E+27 2E+27 1E hν (ev) 2 photons of energy 0.5 E g < hν< E g are converted to 1 photon of hν> E g

25 Down-Conversion for a Single Junction 4E+27 photons/(m 2 ev) 3E+27 2E+27 1E hν (ev) 1 photon of energy hν> 2 E g is converted into 2 photons of hν> E g

26 Up & Down-Conversion Together 100% Efficiency (AM1.5) Normalized efficiency Ge Cu 2 S GaAs a-si:h a-si:h:f Si CdS I. Lubomirsky, D. Cahen (2005) E g

27 Nanoscience in (Solar) Energy

28 END Thank You

29 Maximum efficiency for an ideal multigap system With optical losses Bennett and Olsen, 1988, IEEE PVSC, p. 868

30 Basic Cell Characteristics i (ma/cm 2 ) Potential (V) Voc 769 mv Jsc 16.2 ma/cm 2 Fill Factor 64.3 % Efficiency 8.35 % Potential (V) P (µw/cm 2 )

31 The Nanoporous Electrode wide band-gap semiconductor: TiO 2, SnO 2,Nb 2 O 5, ZnO, SrTiO 3 transparent electrode - visible roughness factor = ~100/µm typical thickness 1-15 µm Conductive Substrate Conductive Substrate µm d=nm

32 Dye Sensitized Solar Cell (DSSC) dye ox red d=nm µm Conductive Substrate conductive substrate

33 Dye Sensitized Solar Cell - Fabrication

34 High Surface Area Electrode Conductive Substrate Conductive Substrate Conductive Substrate Conductive Substrate Conductive Substrate Conductive Substrate Nanoporous Electrode