Arturo Morales AcevedoCINVESTAV del IPN

Electrical Engineering Department

PV Research & Innovation perspectives

LIFyCS

1er. Taller de Innovación

Fotovoltaica y de Celdas Solares

Solar Irradiation in MexicoAnnual daily average

Units are in kW-h/m2

4

Electrical Energy for

rural regions

Grid-connected Photovoltaic SystemsNet Metering

220 houses with a 1 kW PV system in Mexicali, B. C.

How does a solar cell work?

Energy Losses in a conventional

Solar Cell

Diverse Technologies

Solar Cells

Silicon

III-V

II-VI

Polycristalline

Si Monocristalline ········Large scale production

Si Multicristalline ········ Large scale production

Si microcristalline ········ Small production

Si amorphous ········ Small production

GaAs ·······Space applications

InP ·······Space applications

CdTe ·······Medium production

CuInGaSe2

CuInSe2, CuInS2········Small production

other Dye Sensitized/Organic ········I&D

Si spherical ········I&D or Pilot production

Si ribbon ········ Small production

Present situation

1st solar cell generation

Present technology for

silicon solar cells

Typical conversion efficiencies 13-17%, but

the highest laboratory efficiency is 24-25%

PV radio-telephone system

installed in rural Puebla

First PV system using

silicon solar cells and

modules made in

CINVESTAV-Mexico

in 1977.

2nd solar cell generation

CuInGaSe2 thin film solar cells

Solar cells

made by Honda

in Japan, with

efficiencies of 11 -

12%. The highest

reported efficiency

is 20% (small

area).

Subestrate structure

CdS/CdTe thin film solar cells

Wu, X., Keane, J.C., Dhere, R.G., DeHart, C., Albin, D.S., Duda, A., Gessert,

T.A., Asher, S., Levi, D.H., Sheldon, P., 2001a. 16.5%-efficient CdS/CdTe

polycrystalline thin-film solar cells. In: Proceedings of 17th European PVSEC,

pp. 995–1000.

Maximum

efficiency = 16.5%

Thin film amorphous silicon solar cell

Carrier transport is different

than for conventional silicon

solar cells. Carrier

recombination is larger, and

then the efficiency is very

much less.

Maximum

efficiencies

around 12.7%

Solar radiation

Hybrid HIT solar cells

Amorphous silicon

Crystalline Silicon

Efficiencies near

23% in Industrial

scale (Sanyo)

Low temperature

processing

Amorphous silicon

Schematics of a “plastic” solar cellPET - Polyethylene terephthalate, ITO - Indium Tin Oxide, PEDOT:PSS –

[Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)], Active Layer

(usually a polymer:fullerene blend), Al - Aluminum.

Solar cells based on polymers

Dye sensitized solar cellsPhoto-electrochemical Cells

• Nano-porous metallic oxide with a large

exposed surface.

• luminous absorption by the dye molecules.

• Electron and hole transport in the solid and

ion transport in the solution.

Dye ZnO nanorod based solar cells

3rd solar cell generation

New concepts for 3rd generation

solar cells

More energy obtained from solar radiation with:

I. More participating bands:

• Tandem, intermediate bands and spectral

separation.

II. More work from each absorbed photon:

• Impact ionization and “hot carriers”.

III. Apropriate photon redistribution:

• Photon “up” and “down” conversion.

Multi-junction tandem solar cells

Tandem + solar radiation concentration

Concentrating (CPV)

systems will use very

expensive, but highly

efficient solar cells in

order to have PV

energy cost reduction.

It can be shown that

efficiency of a solar

cell ideally increases

when the radiation

intensity increases.

Quantization Effects

Size Quantum Effects

• Dramatic variation of optical and electronic properties.

• Large blue shift of the absorption edge.

• Conservation of momentum relaxed. Crystal momentum is not a good quantum number.

• Greatly enhanced exciton absorption at 300 K.

• Slowed relaxation and cooling (~10X) of photogenerated hot electrons and holes.

• Coulomb coupling and Auger processes greatly enhanced (including exciton multi-plication).

• Conversion of indirect semiconductors to direct semiconductors.

• Discrete energy levels / structured absorption and photoluminescence spectra.

• Greatly enhanced oscillator strength per unit volume (absorption coefficient).

• Greatly enhanced non-linear optical properties.

• Greatly modified pressure dependence of phase changes and direct to indirect transitions.

• Efficient anti-Stokes luminescence.

Enhanced Multiple Exciton

Generation

Silicon Nanocrystals

MEG in Silicon Nanocrystals

Photonic conversion

Silicon Rich Oxide

Zhenrui Yu, Mariano Aceves-Mijares andMarco Antonio Ipiña Cabrera

Nanotechnology 17 (2006) 3962–3967

Polymorphous Silicon

A. Remolina, B. M. Monroy, M. F. García-Sánchez, A. Ponce,M. Bizarro, J. C. Alonso, A. Ortiz and G. Santana

Nanotechnology 20 (2009) 245604

Nanoparticle Plasmonic

Solar Cells

A group at ANU measured an enhanced photocurrent attributed to the increased trapping of light scattered into a thin-film silicon cell by silver metal nano-particles excited at their surface plasmon resonance.

Perspectives for the contribution of solar energy to the

world energy supply for this century

Conclusion

Further research and development is needed in

order to achieve new kinds of solar cells which

are competitive with other electrical energy

sources. High efficiencies and low costs are both

required.

PV solar energy will become a significant part of

the total world energy by 2050, based on

innovation. Then, at the end of this century, solar

PV electricity will become the most important

energy source in the world.

Costo de algunos materiales

para celdas solares

Wadia, C., Alivisatos, A., Kammen, D. M., 2009. Environ. Sci. Technol 43, 6.