TY - JOUR

T1 - Equivalent performance in three-terminal and four-terminal tandem solar cells

AU - Schnabel, Manuel

AU - Rienacker, Michael

AU - Warren, Emily L.

AU - Geisz, John F.

AU - Peibst, Robby

AU - Stradins, Paul

AU - Tamboli, Adele C.

N1 - Funding Information: Manuscript received May 21, 2018; revised July 27, 2018; accepted August 9, 2018. Date of publication September 5, 2018; date of current version October 26, 2018. This work was supported in part by the Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the U.S. Department of Energy under Contract DE-AC36-08GO28308, in part by the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy Solar Energy Technologies Office under Contract DE-00030299, in part by the German State of Lower Saxony (funding at ISFH), the German Federal Ministry for Economics and Energy (BMWi) within the research project “EASi” under Grant FKZ0324040, and in part by EU’s FP7 within the research project “HERCULES” under Grant 608498. (Corresponding author: Adele C. Tamboli.) M. Schnabel, E. L. Warren, J. F. Geisz, P. Stradins, and A. C. Tamboli are with the National Renewable Energy Laboratory, Golden, CO 80401 USA (e-mail:, manuel.schnabel@nrel.gov; Emily.Warren@nrel.gov; john.geisz@nrel.gov; pauls.stradins@nrel.gov; adele.tamboli@nrel.gov). Publisher Copyright: © 2018 IEEE. Copyright: Copyright 2018 Elsevier B.V., All rights reserved.

PY - 2018/11

Y1 - 2018/11

N2 - Tandem or multijunction solar cells are a promising method to circumvent the efficiency limit of single-junction solar cells, but there is ongoing debate over how best to interconnect the subcells in a tandem cell. In addition to four-terminal and two-terminal tandem cell architectures, a new three-terminal tandem cell architecture has recently been demonstrated, which features a standard two-terminal (front-back) circuit as well as an interdigitated back contact (IBC) circuit connected to the bottom cell. It has no middle contacts, and thus, maintains some of the simplicity of a two-terminal tandem. In this study, we measure four-terminal GaInP//Si and GaInP/GaAs//Si tandem cells in four-terminal and three-terminal configurations by connecting wires to mimic a three-terminal architecture. We demonstrate that both modes allow the same efficiencies exceeding 30% to be attained. Furthermore, we show that the IBC circuit not only collects excess power from the bottom cell, but that it can inject power into the bottom cell if it is current limiting the front-back circuit, enabling four-terminal performance in monolithic structures, regardless of which cell delivers less current.

AB - Tandem or multijunction solar cells are a promising method to circumvent the efficiency limit of single-junction solar cells, but there is ongoing debate over how best to interconnect the subcells in a tandem cell. In addition to four-terminal and two-terminal tandem cell architectures, a new three-terminal tandem cell architecture has recently been demonstrated, which features a standard two-terminal (front-back) circuit as well as an interdigitated back contact (IBC) circuit connected to the bottom cell. It has no middle contacts, and thus, maintains some of the simplicity of a two-terminal tandem. In this study, we measure four-terminal GaInP//Si and GaInP/GaAs//Si tandem cells in four-terminal and three-terminal configurations by connecting wires to mimic a three-terminal architecture. We demonstrate that both modes allow the same efficiencies exceeding 30% to be attained. Furthermore, we show that the IBC circuit not only collects excess power from the bottom cell, but that it can inject power into the bottom cell if it is current limiting the front-back circuit, enabling four-terminal performance in monolithic structures, regardless of which cell delivers less current.

KW - Absorption

KW - III-V semiconductor materials

KW - photovoltaic Cells

KW - Silicon

UR - http://www.scopus.com/inward/record.url?scp=85052871329&partnerID=8YFLogxK

U2 - 10.1109/JPHOTOV.2018.2865175

DO - 10.1109/JPHOTOV.2018.2865175

M3 - Article

AN - SCOPUS:85052871329

VL - 8

SP - 1584

EP - 1589

JO - IEEE Journal of Photovoltaics

JF - IEEE Journal of Photovoltaics

SN - 2156-3381

IS - 6

M1 - 8454791

ER -