Sun’s energy
SOLAR CELLS
First steps; discovery of the PV effect
Becquerel, A. E. "Le spectre solaire et la constitution de
la lumière électrique." C. R. l'Acad. Sci., 1839-1841.
"shining light on an electrode submerged in a
conductive solution would create an electric
current."
Alexandre Edmond Becquerel
1839
First steps; discovery of the PV effect
Following the discoveries of photovoltaic properties of selenium (1873) and
selenium-platinum junction (1876) ;
Willoughby SMITH,
"Effect of Light on Selenium during the
passage of an Electric Current",
Nature, 20 February 1873, p.303.
W. G. Adams and R. E. Day, “The action of
light on selenium”, Proc. Roy. Soc. 25
(1876):113-17.
First steps; discovery of the PV effect
Following the discoveries of photovoltaic properties of selenium (1873) and
selenium-platinum junction (1876) ;
In 1883, first solar cell was built by Charles Fritts
with 1% efficiency. Very thin gold layer on top of
selenium.
Asking “How?” and “Why?”
Albert Einstein - On a heuristic viewpoint
concerning the production and transformation
of light. Annalen der Physik 17:132-148, 1905
Proved photoelectric effect.
R.A.Millikan, “A Direct Photoelectric
Determination of Planck’s ’h’ ”, Physical
Review 7, 355–388 (1916).
Searching for “Cold Peace” in space
•In the early 1950s researches on solar cells gained speed (RCA labs, AT&T, Bell labs)
•First practical device fabricated in Bell labs with a 6% efficiency
•On 17th March 1958, the first satellite powered by solar cells, Vanguard I, was
launched (Hoffman electronics, 9% efficiency).
Searching for “Cold Peace” in space
•In the early 1950s researches on solar cells gained speed (RCA labs, AT&T, Bell labs)
•Fierst prtactical device fabricated in Bell labs with a 6% efficiency
•On 17th March, the first satellite powered by solar cells, Vanguard I, was launched
(Hoffman electronics, 9% efficiency).
•Followed by Explorer III, Vanguard II (USA), and Sputnik III (USSR)
•1955 – First sun-powered automobile Illinois
•1963 - Sharp Corporation – first photovoltaic module from silicon solar cells
•1970 – USSR – first highly effective GaAs heterostructure solar cells were fabricated
by Zhores Alferov
Companies’ era
•In 1980s many companies were established and began a race to increase the output
efficiency.
•By the introduction of MOCVD the efficiency of GaAs solar cell increased to 17%.
•1989 – ASEC- changing the substrate material led to invention of dual junction cells
(20 %).
•Using multiple junction solar cells the efficiencies increased to 30 % levels in 2000s.
Record efficiencies (multiple-junction solar cells)
Christiana Honsberg and Allen Barnett
University of Delaware
42.8 %
Dr. Frank Dimroth
Fraunhofer Institute for Solar Energy Systems
41.1 %
John Geisz
National Renewable Energy Laboratory (NREL)
40.8 %
WHAT IS A SOLAR CELL?
Basic loss mechanisms
•Reflectance losses
•Thermodynamic losses
•Recombination losses
Crystalline silicon
c-Si
Czochralski method
Thin film
•Advantageous due to less material usage
•Flexibility
•Lighter weights
•CdTe (easy to deposit, toxicity)
•CIS (CuInSe2) and CIGS (CuInxGa(1-x)Se2)
•GaAs multijunction (generally for space)
•Light absorbing dyes (DSSC) (Ruthenium metal organic dye )
•Organic/Polymer
Concentrators
Concentrators
Concentrators
Wilfred G.J.H.M. van Sark, et. al., Optics Express,
16(26), 21773(2008).
Concentrators
dyes:
•4-(dicyanomethylene)-2-t-butyl-6- (1,1,7,7tetramethyljulolidyl-9-enyl)-4H -pyran (DCJTB)
•platinum tetraphenyltetrabenzoporphyrin
[Pt(TPBP)]
Host material: tris(8hydroxyquinoline) aluminum (AlQ3)
Science, 321, 11 July 2008.
Concentrators
Science, 321, 11 July 2008.
Concentrators
Comparison of an organic dye and QD
Rowan, et. Al., Adv. Matr. Concepts for Luminescent Solar Concentrators, 14(5), 1312(Oct, 2008).
Concentrators
Quantum Dot Solar Concentrators
For efficient light concentration QDs and the carrier material
should be compatible. It is important to the carrier material
have following properties:
•Low absorption coefficient
•Solubility with QDs
•High luminescence when cast with QDs
•Chemical durability
•Non-toxic
•Low cost
In addition the quantum dots should;
•Efficiently absorb solar energy
•Are intensely luminescent in the specral region of PV cell’s
maximum sensitivity
•Mechanically strong
•Chemically stable
•Preserve their spectral-luminescent characteristics
Concentrators
Quantum Dot Solar Concentrators
Concentrators
Quantum Dot Solar Concentrators
Concentrators
Quantum Dot Solar Concentrators
Concentrators
Quantum Dot Solar Concentrators
Concentrators
Quantum Dot Solar Concentrators
Result: 77% light retention