TY - JOUR

T1 - Theoretical efficiency of 3rd generation solar cells

T2 - Comparison between carrier multiplication and down-conversion

AU - Abrams, Zeev R.

AU - Gharghi, Majid

AU - Niv, Avi

AU - Gladden, Chris

AU - Zhang, Xiang

N1 - Funding Information:
ZRA thanks Prof. Viorel Badescu for his helpful discussion. This work was supported by the U.S. Department of Energy, Basic Energy Sciences Energy Frontier Research Center (DoE-LMI-EFRC) under award DOE DE-AC02-05CH11231 . ZRA acknowledges Government support under and awarded by DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a.

PY - 2012/4/1

Y1 - 2012/4/1

N2 - Two of the methods of exceeding the detailed balance limit for a single junction solar cell are down-converting high energy photons to produce two photons and carrier multiplication, whereby high energy photons produce more than one electronhole pair. Both methods obey the conservation of energy in similar ways, and effectively produce a higher current in the solar cell. Due to this similarity, it has been assumed in the literature that there is no thermodynamic difference between the two methods. Here, we analyzed the two methods using a generalized approach based on Kirchhoffs law of radiation and develop a new model for carrier multiplication. We demonstrate that there is an entropic penalty to be paid for attempting to accomplish all-in-one splitting in carrier multiplication systems, giving a small thermodynamic and therefore efficiency advantage to spectral splitting prior to reaching the solar cell. We show this analytically using a derivation of basic thermodynamic identities; numerically by solving for the maximal efficiency; and generally using heat-generation arguments. Our result provides a new limit of entropy generation in solar cells beyond the existing literature, and a new distinction among 3rd generation photovoltaic technologies.

AB - Two of the methods of exceeding the detailed balance limit for a single junction solar cell are down-converting high energy photons to produce two photons and carrier multiplication, whereby high energy photons produce more than one electronhole pair. Both methods obey the conservation of energy in similar ways, and effectively produce a higher current in the solar cell. Due to this similarity, it has been assumed in the literature that there is no thermodynamic difference between the two methods. Here, we analyzed the two methods using a generalized approach based on Kirchhoffs law of radiation and develop a new model for carrier multiplication. We demonstrate that there is an entropic penalty to be paid for attempting to accomplish all-in-one splitting in carrier multiplication systems, giving a small thermodynamic and therefore efficiency advantage to spectral splitting prior to reaching the solar cell. We show this analytically using a derivation of basic thermodynamic identities; numerically by solving for the maximal efficiency; and generally using heat-generation arguments. Our result provides a new limit of entropy generation in solar cells beyond the existing literature, and a new distinction among 3rd generation photovoltaic technologies.

KW - Carrier multiplication

KW - Down-conversion

KW - Energy conversion efficiency

KW - Entropy

KW - Multiple exciton generation

UR - http://www.scopus.com/inward/record.url?scp=84862819850&partnerID=8YFLogxK

U2 - 10.1016/j.solmat.2011.12.019

DO - 10.1016/j.solmat.2011.12.019

M3 - Article

AN - SCOPUS:84862819850

VL - 99

SP - 308

EP - 315

JO - Solar Energy Materials and Solar Cells

JF - Solar Energy Materials and Solar Cells

SN - 0927-0248

ER -