TY - JOUR
T1 - A semi-analytical model for semiconductor solar cells
AU - Ding, D.
AU - Johnson, Shane
AU - Yu, S. Q.
AU - Wu, S. N.
AU - Zhang, Yong-Hang
N1 - Funding Information:
This work is supported by the Science Foundation Arizona Contract Nos. SRG 0190-07 and SRG 0339-08, the Air Force Research Laboratories/Space Vehicles Directorate Contract No. FA9453-08-2-0228, and the National Science Foundation Grant No. 1002114. The authors thank Swee H. Lim, Shi Liu, Jing-Jing Li, and Shuming Wang for valuable discussions on some of the topics in this paper.
PY - 2011/12/15
Y1 - 2011/12/15
N2 - A semi-analytical model is constructed for single- and multi-junction solar cells. This model incorporates the key performance aspects of practical devices, including nonradiative recombination, photon recycling within a given junction, spontaneous emission coupling between junctions, and non-step-like absorptance and emittance with below-bandgap tail absorption. Four typical planar structures with the combinations of a smooth/textured top surface and an absorbing/reflecting substrate (or backside surface) are investigated, through which the extracted power and four types of fundamental loss mechanisms, transmission, thermalization, spatial-relaxation, and recombination loss are analyzed for both single- and multi-junction solar cells. The below-bandgap tail absorption increases the short-circuit current but decreases the output and open-circuit voltage. Using a straightforward formulism this model provides the initial design parameters and the achievable efficiencies for both single- and multiple-junction solar cells over a wide range of material quality. The achievable efficiency limits calculated using the best reported materials and AM1.5 G one sun for GaAs and Si single-junction solar cells are, respectively, 27.4 and 21.1 for semiconductor slabs with a flat surface and a non-reflecting index-matched absorbing substrate, and 30.8 and 26.4 for semiconductor slabs with a textured surface and an ideal 100 reflecting backside surface. Two important design rules for both single- and multi-junction solar cells are established: i) the optimal junction thickness decreases and the optimal bandgap energy increases when nonradiative recombination increases; and ii) the optimal junction thickness increases and the optimal bandgap energy decreases for higher solar concentrations.
AB - A semi-analytical model is constructed for single- and multi-junction solar cells. This model incorporates the key performance aspects of practical devices, including nonradiative recombination, photon recycling within a given junction, spontaneous emission coupling between junctions, and non-step-like absorptance and emittance with below-bandgap tail absorption. Four typical planar structures with the combinations of a smooth/textured top surface and an absorbing/reflecting substrate (or backside surface) are investigated, through which the extracted power and four types of fundamental loss mechanisms, transmission, thermalization, spatial-relaxation, and recombination loss are analyzed for both single- and multi-junction solar cells. The below-bandgap tail absorption increases the short-circuit current but decreases the output and open-circuit voltage. Using a straightforward formulism this model provides the initial design parameters and the achievable efficiencies for both single- and multiple-junction solar cells over a wide range of material quality. The achievable efficiency limits calculated using the best reported materials and AM1.5 G one sun for GaAs and Si single-junction solar cells are, respectively, 27.4 and 21.1 for semiconductor slabs with a flat surface and a non-reflecting index-matched absorbing substrate, and 30.8 and 26.4 for semiconductor slabs with a textured surface and an ideal 100 reflecting backside surface. Two important design rules for both single- and multi-junction solar cells are established: i) the optimal junction thickness decreases and the optimal bandgap energy increases when nonradiative recombination increases; and ii) the optimal junction thickness increases and the optimal bandgap energy decreases for higher solar concentrations.
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U2 - 10.1063/1.3671061
DO - 10.1063/1.3671061
M3 - Article
AN - SCOPUS:84855313418
SN - 0021-8979
VL - 110
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 12
M1 - 123104
ER -