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Recent results for single‐junction and tandem quantum well solar cells
Author(s) -
Adams J. G. J.,
Browne B. C.,
Ballard I. M.,
Connolly J. P.,
Chan N. L. A.,
Ioannides A.,
Elder W.,
Stavrinou P. N.,
Barnham K. W. J.,
EkinsDaukes N. J.
Publication year - 2011
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.1069
Subject(s) - solar cell , quantum well , optoelectronics , materials science , tandem , theory of solar cells , quantum efficiency , spontaneous emission , band gap , solar cell efficiency , optics , physics , laser , composite material
Abstract The band gap of the quantum well (QW) solar cell can be adapted to the incident spectral conditions by tailoring the QW depth. The single‐junction strain‐balanced quantum well solar cell (SB‐QWSC) has achieved an efficiency of 28.3%. The dominant loss mechanism at the high concentrator cell operating bias is due to radiative recombination, so a major route to further efficiency improvement requires a restriction of the optical losses. It has been found that (100) biaxial compressive strain suppresses a mode of radiative recombination in the plane of the QWs. As biaxial strain can only be engineered into a solar cell on the nanoscale, SB‐QWSCs are seen to have a fundamental efficiency advantage over equivalent bulk cells. Strain‐balanced quantum wells in multi‐junction solar cells can current match the sub‐cells without the introduction of dislocations. Calculations are shown which predict efficiency limits as a function of QW absorption and band gap for such cells. A dual‐junction InGaP/GaAs solar cell with QWs in the bottom sub‐cell has been grown and characterized. Laboratory and calculated efficiencies relative to control cells are presented for the reported cell and a modeled device, respectively. Copyright © 2011 John Wiley & Sons, Ltd.