Environmentally printing efficient organic tandem solar cells with high fill factors: A guideline towards 20% power conversion efficiency

Ning Li*, Derya Baran, George D. Spyropoulos, Hong Zhang, Stephane Berny, Mathieu Turbiez, Tayebeh Ameri, Frederik C. Krebs, Christoph J. Brabec

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

121 Scopus citations


The tandem concept involves stacking two or more cells with complementary absorption spectra in series or parallel connection, harvesting photons at the highest possible potential. It is strongly suggested that the roll-to-roll production of organic solar cells will employ the tandem concept to enhance the power conversion efficiency (PCE). However, due to the undeveloped deposition techniques, the challenges in ink formulation as well as the lack of commercially available high performance active materials, roll-to-roll fabrication of highly efficient organic tandem solar cells currently presents a major challenge. The reported high PCE values from lab-scale spin-coated devices are, of course, representative, but not helpful for commercialization. Here, organic tandem solar cells with exceptionally high fill factors and PCE values of 7.66% (on glass) and 5.56% (on flexible substrate), which are the highest values for the solution-processed tandem solar cells fabricated by a mass-production compatible coating technique under ambient conditions, are demonstrated. To predict the highest possible performance of tandem solar cells, optical simulation based on experimentally feasible values is performed. A maximum PCE of 21% is theoretically achievable for an organic tandem solar cell based on the optimized bandgaps and achieved fill factors.

Original languageEnglish (US)
Article number1400084
JournalAdvanced Energy Materials
Issue number11
StatePublished - Aug 5 2014
Externally publishedYes


  • flexible electronics
  • large-scale production
  • organic photovoltaics
  • organic solar cells
  • solution processing

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Materials Science


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