Physical Society Colloquium
The Opto-Electronic Physics Which Just Broke the Efficiency
Record in Solar Cells
Electrical Engineering and Computer Sciences
UC Berkeley
Solar cell science and technology is changing. New efficiency records are being
set. Alta Devices has reached 28.8% efficiency in a thin film single-junction
cell at 1-sun, and 30.8% efficiency in a thin-film dual junction cell at
1-sun.
Counter-intuitively, efficient external fluorescence is a necessity for
approaching the ultimate limits. A great Solar Cell also needs to be a great
Light Emitting Diode. Why would a solar cell, intended to absorb light,
benefit from emitting light? Although it is tempting to equate light emission
with loss, paradoxically, light emission actually improves the open-circuit
voltage, and the efficiency.
The single-crystal thin film technology that achieved these high efficiencies,
is created by epitaxial liftoff, and can be produced at cost well below the
other less efficient thin film solar technologies. The path is now open to
a 30% efficient photovoltaic technology that can be produced at low cost.
Suggested Reading: “Intense Internal and External Fluorescence
as Solar Cells Approach the Shockley-Queisser Efficiency Limit”,
O. D. Miller, Eli Yablonovitch, and S. R. Kurtz, IEEE
J. Photovoltaics, vol. 2, pp. 303-311 (2012).“The
Opto-Electronics of Solar Cells”, E. Yablonovitch and
O. D. Miller, IEEE Photonics Society Newsletter, vol. 27,
No. 1, p. 4, (February 2013)
Friday, October 4th 2013, 15:30
Ernest Rutherford Physics Building, Key Auditorium (room 112)
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