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Title: III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint

Abstract

Solar cells made from bulk crystalline silicon (c-Si) dominate the market, but laboratory efficiencies have stagnated because the current record efficiency of 26.3% is already very close to the theoretical limit of 29.4% for a single-junction c-Si cell. In order to substantially boost the efficiency of Si solar cells we have been developing stacked III-V/Si tandem cells, recently attaining efficiencies above 32% in four-terminal configuration. In this contribution, we use state-of-the-art III-V cells coupled with equivalent circuit simulations to compare four-terminal (4T) to three- and two-terminal (3T, 2T) operation. Equivalent circuit simulations are used to show that tandem cells can be operated just as efficiently using three terminals as with four terminals. However, care must be taken not to overestimate 3T efficiency, as the two circuits used to extract current interact, and a method is described to accurately determine this efficiency. Experimentally, a 4T GaInP/Si tandem cell utilizing an interdigitated back contact cell is shown, exhibiting a 4T efficiency of 31.5% and a 2T efficiency of 28.1%. In 3T configuration, it is used to verify the finding from simulation that 3T efficiency is overestimated when interactions between the two circuits are neglected. Considering these, a 3T efficiency approaching the 4Tmore » efficiency is found, showing that 3T operation is efficient, and an outlook on fully integrated high-efficiency 3T and 2T tandem cells is given.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
OSTI Identifier:
1371528
Report Number(s):
NREL/CP-5J00-67829
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at 2017 IEEE 44th Photovoltaic Specialists Conference (PVSC), 25-30 June 2017, Washington, DC
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; crystalline silicon; tandem cells; high-efficiency

Citation Formats

Schnabel, Manuel, Klein, Talysa R., Jain, Nikhil, Essig, Stephanie, Schulte-Huxel, Henning, Warren, Emily, van Hest, Maikel F. A. M., Geisz, John, Stradins, Paul, Tamboli, Adele, Rienacker, Michael, Merkle, Agnes, Schmidt, Jan, Brendel, Rolf, and Peibst, Robby. III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint. United States: N. p., 2017. Web.
Schnabel, Manuel, Klein, Talysa R., Jain, Nikhil, Essig, Stephanie, Schulte-Huxel, Henning, Warren, Emily, van Hest, Maikel F. A. M., Geisz, John, Stradins, Paul, Tamboli, Adele, Rienacker, Michael, Merkle, Agnes, Schmidt, Jan, Brendel, Rolf, & Peibst, Robby. III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint. United States.
Schnabel, Manuel, Klein, Talysa R., Jain, Nikhil, Essig, Stephanie, Schulte-Huxel, Henning, Warren, Emily, van Hest, Maikel F. A. M., Geisz, John, Stradins, Paul, Tamboli, Adele, Rienacker, Michael, Merkle, Agnes, Schmidt, Jan, Brendel, Rolf, and Peibst, Robby. 2017. "III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint". United States. doi:. https://www.osti.gov/servlets/purl/1371528.
@article{osti_1371528,
title = {III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint},
author = {Schnabel, Manuel and Klein, Talysa R. and Jain, Nikhil and Essig, Stephanie and Schulte-Huxel, Henning and Warren, Emily and van Hest, Maikel F. A. M. and Geisz, John and Stradins, Paul and Tamboli, Adele and Rienacker, Michael and Merkle, Agnes and Schmidt, Jan and Brendel, Rolf and Peibst, Robby},
abstractNote = {Solar cells made from bulk crystalline silicon (c-Si) dominate the market, but laboratory efficiencies have stagnated because the current record efficiency of 26.3% is already very close to the theoretical limit of 29.4% for a single-junction c-Si cell. In order to substantially boost the efficiency of Si solar cells we have been developing stacked III-V/Si tandem cells, recently attaining efficiencies above 32% in four-terminal configuration. In this contribution, we use state-of-the-art III-V cells coupled with equivalent circuit simulations to compare four-terminal (4T) to three- and two-terminal (3T, 2T) operation. Equivalent circuit simulations are used to show that tandem cells can be operated just as efficiently using three terminals as with four terminals. However, care must be taken not to overestimate 3T efficiency, as the two circuits used to extract current interact, and a method is described to accurately determine this efficiency. Experimentally, a 4T GaInP/Si tandem cell utilizing an interdigitated back contact cell is shown, exhibiting a 4T efficiency of 31.5% and a 2T efficiency of 28.1%. In 3T configuration, it is used to verify the finding from simulation that 3T efficiency is overestimated when interactions between the two circuits are neglected. Considering these, a 3T efficiency approaching the 4T efficiency is found, showing that 3T operation is efficient, and an outlook on fully integrated high-efficiency 3T and 2T tandem cells is given.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 7
}

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  • In this paper, two-dimensional (2D) simulation of interdigitated back contact silicon heterojunction (IBC-SHJ) solar cells is presented using Sentaurus Device, a software package of Synopsys TCAD. A model is established incorporating a distribution of trap states of amorphous-silicon material and thermionic emission across the amorphous-silicon / crystalline-silicon heterointerface. The 2D nature of IBC-SHJ device is evaluated and current density-voltage (J-V) curves are generated. Optimization of IBC-SHJ solar cells is then discussed through simulation. It is shown that the open circuit voltage (VOC) and short circuit current density (JSC) of IBC-SHJ solar cells increase with decreasing front surface recombination velocity. Themore » JSC improves further with the increase of relative coverage of p-type emitter contacts, which is explained by the simulated and measured position dependent laser beam induced current (LBIC) line scan. The S-shaped J-V curves with low fill factor (FF) observed in experiments are also simulated, and three methods to improve FF by modifying the intrinsic a-Si buffer layer are suggested: (i) decreased thickness, (ii) increased conductivity, and (iii) reduced band gap. With all these optimizations, an efficiency of 26% for IBC-SHJ solar cells is potentially achievable.« less
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