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

Manuel Schnabel, Marinus Van Hest, John Geisz, Pauls Stradins, Adele Tamboli, Emily Warren, Michael Rienacker, Stephanie Essig, Robby Peibst, Agnes Merkle, Jan Schmidt, Rolf Brendel

Research output: Contribution to conferencePaper


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.
Original languageAmerican English
Number of pages7
StatePublished - 2017
Event2017 IEEE 44th Photovoltaic Specialists Conference (PVSC) - Washington, D.C.
Duration: 25 Jun 201730 Jun 2017


Conference2017 IEEE 44th Photovoltaic Specialists Conference (PVSC)
CityWashington, D.C.

NREL Publication Number

  • NREL/CP-5J00-67829


  • crystalline silicon
  • high-efficiency
  • tandem cells


Dive into the research topics of 'III-V/Si Tandem Cells Utilizing Interdigitated Back Contact Si Cells and Varying Terminal Configurations: Preprint'. Together they form a unique fingerprint.

Cite this