Presentation is loading. Please wait.

Presentation is loading. Please wait.

Third Generation Solar cells

Published byBaldwin Mason Modified over 8 years ago

Similar presentations

Presentation on theme: "Third Generation Solar cells"— Presentation transcript:

1 Third Generation Solar cells
1

2 Outline Sunlight spectrum How a classical solar cell works
First generation solar cells Second generation solar cells The main losses in solar cells Third generation solar cells Band gap engineering Multiple exciton generation Hot carrier solar cells Up conversion Down conversion Tandem cells Summary

3 Sunlight Spectrum Sunlight consists of a broad range of spectrum
The photon energy depends on the photon wavelength: Ephot = hc/λ Harnessing the great amount of sunlight energy Solar Radiation Spectrum Online: 3

4 How a Classical Solar Cell Works
Photovoltaic cell is a device that converts solar energy into electricity by the photovoltaic effect Energy of the incident photon should be greater than or equal to the band gap of the semiconductor If an exciton is created in space charge region, its electron-hole components would be separated Electric Field 4

5 First Generation Solar Cells
Single crystal silicon wafers Dominant in the commercial production of solar cells Consist of a large-area, single layer p-n junction Best crystalline Si solar cell efficiency: ~ 25% Advantages Broad spectral absorption range High carrier mobility Disadvantages Most of photon energy is wasted as heat Require expensive manufacturing technologies 5

6 Second Generation Solar Cells
Thin-film Technologies Amorphous silicon Polycrystalline silicon Cadmium Telluride (CdTe) Best large area Si-based solar cell efficiency: ~ 22% Advantages Low material cost Reduced mass Disadvantages Toxic material (Cd), Scarce material (Te) 6

7 The Main Losses in Solar Cells
Sub bandgap and Lattice thermalisation losses acount for more than 50% of the total loss Energy Lattice thermalisation loss Junction loss Contact loss Sub bandgap loss qV Recombination loss

8 Third Generation Solar Cells
Solar cells which use concepts that allow for a more efficient utilization of the sunlight than FG and SG solar cells The biggest challenge is reducing the cost/watt of delivered solar electricity Third generation solar cells pursue More efficiency More abundant materials Non-toxic material Durability Efficiency and cost projections Third Generation First Generation Second Generation ARC Photovoltaics center of Excellence, University of New Soth Wales, Annual Report (2007) 8

9 Third Generation Solar Cells
Band gap engineering using quantum confinment effect Multiple Exciton Generation Hot Carrier Solar Cell Up Conversion Down Conversion Tandem Cells

10 Band Gap Engineering Excitonc Bohr radius
Quantum confinement Discrete energy levels Excitonc Bohr radius the size of the band gap is controlled simply by adjusting the size of the dot. Thin film Si band gap: Eg = 1.12 eV 2 nm QD Si band gap: Eg = 1.7 eV Enhanced impact ionization (inverse Auger recombination) Greatly enhanced non-linear optical properties Egap 10

11 Multiple Exciton Generation
Objective: fighting termalization In quantum dots, the rate of energy dissipation is significantly reduced One photon creates more than one exciton via impact ionization Higher photocurrent via impact ionization (inverse Auger process) Multiple exciton generation evidence PbSe (lead selenide) QDs Egap Egap 11

12 Hot Carrier Solar Cell Objective: fighting thermalization
Energy selective contacts Need to slow carrier cooling Higher photovoltage via hot electron transport The idea is to suppress the Klemens transitions ELO>2ELA such that LO→2LA (Klemens mechanism) is forbidden The LO→TO+LA (Ridley mechanism) can occur Hot carrier evidence InN G.J. Conibeer, D. König et al., “Slowing of carrier cooling in hot carrier solar cells,” Thin Solid Films, 516, , (2008) 12

13 Up Conversion Objective: transforming large wavelength photons into small wavelengh photons Nearly half of the intensity of sunlight is within the invisible infrared region Can be implemented by quantum wells and quantum dots The drawback is that it is a non-linear effect Up conversion evidence: (Erbium) It is far from realization ½ Eg Eg ½ Eg 13

14 Down Conversion Objective: transforming small wavelength photons into large wavelength photons Suitable materials must efficiently absorb high energy photons and reemit more than one photon with sufficient energies can be implemented by quantum wells and quantum dots Down conversion evidence: Multiple exciton generation Egap Eg 2 Eg Eg 14

15 The only proven 3rd generation technique so far
Tandem Cells The only proven 3rd generation technique so far Light Upper cell (absorbs high energy photons) Middle cell (absorbs medium energy photons) Lower cell (absorbs low energy photons) 15

16 Tandem Cells Nanocrystal sizes approaching the excitonic Bohr radius
Small nanocrystals of Si embedded in a silicon dielectric matrix Annealing at 1100 oC Multi-layers containing n-type Si QDs on p-type Si wafers G. Conibeer, M. Green et al., “Silicon quantum dot nanostructures for tandem photovoltaic cells,” Thin Solid Films, 516, , (2008) G. Conibeer, M. Green et al., “Silicon quantum dot nanostructures for tandem photovoltaic cells,” Thin Solid Films, 516, , (2008) 16

17 Tandem Cells Best device in this respect, was the one with 3 nm QDs with an efficiency of 10.6% This is comparable to a conventional p-n junction crystalline silicon solar cells with a non-textured surface ARC Photovoltaics center of Excellence, University of New Soth Wales, Annual Report (2007)

18 Tandem Cells What we can also investigate:
Effect of excitonic Bohr radius Si = 4.9 nm Ge = 24.3 nm Sn = 40 nm The quantum size effects should be more prominent in Tin nanocrystals even for larger sizes of nanocrystals 18

19 Summary Objectives in third generation solar cells Quantum confinment
More efficient Less expensive Readily available Non-toxic Quantum confinment Band gap engineering Multiple exciton generation Already seen in QDs but with very low efficiencies Hot carriers Far from utilization Up conversion So far has not been realized Down conversion Can be utilized through the concept of multiple exciton generation Tandem cells The only proven technique in 3rd generation solar cells 19

20 Acknowledgment I want to sincerely thank my supervisor, professor
G. Palasantzas whose kind attentions led me through the difficulties.

Download ppt "Third Generation Solar cells"

Similar presentations

Solar cells Yogesh Wakchaure.

Solar cells Yogesh Wakchaure.
PRESENTED BY: PROF. S. Y. MENSAH F.A.A.S; F.G.A.A.S UNIVERSITY OF CAPE COAST, GHANA.

PRESENTED BY: PROF. S. Y. MENSAH F.A.A.S; F.G.A.A.S UNIVERSITY OF CAPE COAST, GHANA.
LECTURE- 5 CONTENTS  PHOTOCONDUCTING MATERIALS  CONSTRUCTION OF PHOTOCONDUCTING MATERIALS  APPLICATIONS OF PHOTOCONDUCTING MATERIALS.

LECTURE- 5 CONTENTS  PHOTOCONDUCTING MATERIALS  CONSTRUCTION OF PHOTOCONDUCTING MATERIALS  APPLICATIONS OF PHOTOCONDUCTING MATERIALS.
Applications of Photovoltaic Technologies. 2 Solar cell structure How a solar cell should look like ?  It depends on the function it should perform,

Applications of Photovoltaic Technologies. 2 Solar cell structure How a solar cell should look like ?  It depends on the function it should perform,
Solar Electricity Light energy, one photon at a time.

Solar Electricity Light energy, one photon at a time.
Third Generation Solar cells

Third Generation Solar cells
Silicon Nanowire based Solar Cells

Silicon Nanowire based Solar Cells
Photovoltaic Materials and Technology Philip Griffin 3/02/10 University of Tennessee- Knoxville Department of Physics 14 MW, 70,000.

Photovoltaic Materials and Technology Philip Griffin 3/02/10 University of Tennessee- Knoxville Department of Physics 14 MW, 70,000.
Cell and module construction. Photovoltaic effect and basic solar cell parameters To obtain a potential difference that may be used as a source of electrical.

Cell and module construction. Photovoltaic effect and basic solar cell parameters To obtain a potential difference that may be used as a source of electrical.
Semiconductor Light Detectors ISAT 300 Foundations of Instrumentation and Measurement D. J. Lawrence Spring 1999.

Semiconductor Light Detectors ISAT 300 Foundations of Instrumentation and Measurement D. J. Lawrence Spring 1999.
Smart Grid Management CLIL4U 537672-LLP-1-2013-1-DK-KA2-KA2MP 1.

Smart Grid Management CLIL4U LLP DK-KA2-KA2MP 1.
 Environmental pollution is a serious issue and it is important to take steps on an individual level to reduce it. But now, since it is becoming an international.

 Environmental pollution is a serious issue and it is important to take steps on an individual level to reduce it. But now, since it is becoming an international.
Tin Based Absorbers for Infrared Detection, Part 2 Presented By: Justin Markunas Direct energy gap group IV semiconductor alloys and quantum dot arrays.

Tin Based Absorbers for Infrared Detection, Part 2 Presented By: Justin Markunas Direct energy gap group IV semiconductor alloys and quantum dot arrays.
Photovoltaic Cells (Solar Panels)

Photovoltaic Cells (Solar Panels)
Solar Cell Operation Key aim is to generate power by:

Solar Cell Operation Key aim is to generate power by:
Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 1 Chapter I Introduction June 20, 2015June 20, 2015June 20, 2015.

Department of Aeronautics and Astronautics NCKU Nano and MEMS Technology LAB. 1 Chapter I Introduction June 20, 2015June 20, 2015June 20, 2015.
Solar Energy Robert Kinzler

Solar Energy Robert Kinzler
Solar Cells Outline. Single-Junction Solar Cells. Multi-Junction Solar Cells.

Solar Cells Outline. Single-Junction Solar Cells. Multi-Junction Solar Cells.
Why Use Solar Cells? Low maintenance, long lasting sources of energy Provides cost-effective power supplies for people remote from the main electricity.

Why Use Solar Cells? Low maintenance, long lasting sources of energy Provides cost-effective power supplies for people remote from the main electricity.
Applications. Until very recently silicate glasses were the only type of materials commonly used. Until very recently silicate glasses were the only type.

Applications. Until very recently silicate glasses were the only type of materials commonly used. Until very recently silicate glasses were the only type.

Similar presentations

Ads by Google