I am investigating different types of losses in multi junction solar cell. I came to know that, tunneling junction is a important factor for designing multi junction solar cell. What kind of tunneling losses can occur in solar cell. Any reference regrading this will be extremely helpful. Thanks in advance and all the best with research :)
Dear Uday,
welcome,
The multijunction tandem cell can be modeled as single junction solar cells connected in series. The number of these single junction solar cells is equal to the number of the active junctions in the tandem cell.
The tandem cell must be constructed such that the photocurrent of the equivalent different single junction solar cells is equal which is the current matching condition.
One of the challenges in the multijunction solar cell is that the junction formed between adjacent active junctions must be ohmic and of low resistance. Such intermediate junctions between the active junctions can be made ohmic and of low resistance by making them tunneling junctions.
Stunning junctions are formed by increasing the doping at its sides to the the degeneracy limit which means that the doping must be made higher than the effective density of state. As the doping increases the tunneling current density increases and the resistance of such junctions will decrease satisfying the conditions of the intermediate junctions.
From the electrical point of view these tunneling intermediate junction can be modeled by a series resistance. So, the losses will be included in the total series resistance of the tandem solar cells.
Best wishes
There are loss mechanisms in tunneling junctions are , Interfaces and stresses are among the most influential.
These articles and book chapter may help you
Band Gap Engineering of Multi-Junction Solar Cells: Effects of Series Resistances and Solar Concentration
Scientific Reports volume 7, Article number: 1766 (2017)
doi:10.1038/s41598-017-01854-6
https://www.nature.com/articles/s41598-017-01854-6
Designing III-V multijunction solar cells on silicon
28th European Photovoltaic Solar Energy Conference and Exhibition (2013)
Prog. Photovolt: Res. Appl Volume22, Issue7 July 2014, Pages 810-820
A COPY OF THE PAPER IS HERE https://arxiv.org/ftp/arxiv/papers/1312/1312.2908.pdf
Book Chapter : III-V Solar Cells
Stuart J C Irvine. Materials Challenges: Inorganic Photovoltaic Solar Energy,, Royal Society of Chemistry, pp.209-246, 2014, 978-1-84973-187-4.
Availiable here : https://arxiv.org/ftp/arxiv/papers/1301/1301.1278.pdf
Modelling of Dual-Junction Solar Cells including Tunnel Junction
Advances in Condensed Matter Physics
Volume 2013 (2013), Article ID 546362, 5 pages
http://dx.doi.org/10.1155/2013/546362
https://www.hindawi.com/journals/acmp/2013/546362/
Performance analysis of AlGaAs/GaAs tunnel junctions for ultra-high concentration photovoltaics
I García et al 2012 J. Phys. D: Appl. Phys. 45 045101
https://doi.org/10.1088/0022-3727/45/4/045101
Availiable @ http://oa.upm.es/15404/1/INVE_MEM_2012_134411.pdf
A case study of system power efficiency loss mechanisms in a multijunction, spectral splitting, concentrator solar cell system
Published in: Photovoltaic Specialists Conference (PVSC), 2009 34th IEEE
DOI: 10.1109/PVSC.2009.5411606
https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1014&context=ecepubs
Good question.
Infact Dr. Abdelhalim already provided a detail answer, I just want to add one thing.
If series connected sub-layers of multijunction solar cell are in lattice match condition, optical transparency occurs here, so tunnel junction does not affect strongly to the overall efficiency but if the sub layers are lattice mismatch in extent to 3% to 4%, then tunnel junction affects the performance of cell.
For loss calculation of multijunction solar cell, please google 'spectral p-n junction model' by Bernet et al.
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