Influence of the interface material layers and semiconductor energetic disorder on the open circuit voltage in polymer solar cells

Andrea Zampetti, Amir Hossein Fallahpour, Martina Dianetti, Luigi Salamandra, Francesco Santoni, Alessio Gagliardi, Matthias Auf Der Maur, Francesca Brunetti, Andrea Reale, Thomas M. Brown, Aldo Di Carlo

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 690-699 The relationship between open-circuit voltage (VOC) and the work function (φ) of the interface layers is still a matter of debate in polymer solar cells. Simulations, together with experiments on more than 20 cell architectures based on P3HT:PC60BM, enable the analysis of the physical dependence of VOC on φ. Furthermore, by varying the Gaussian density of states (DOS), it is shown that VOC performance depends significantly also on the DOS.

Material layers at electrode/semiconductor interfaces are fundamental for the photovoltaic properties of polymer solar cells. The relationship between open-circuit voltage (VOC) and the work function (φ) of these interface layers is still a matter of debate. Simulations, together with experiments on over more than 20 cell architectures based on P3HT:PC60BM, enabled us to analyze the physical dependence of VOC on φ. In particular, when the work function of the contacts is well inside the gap we observe that performance depends strongly on even small variations of φ. On the other hand, when it approaches the energy levels of the semiconducting polymers, device operation becomes the most efficient and less sensitive to variations in φ. Furthermore, by varying the Gaussian density of states (DOS) of the active blend we were able to show that VOC performance depends significantly also on the DOS. Our study based on the simultaneous variation of transport layers represents a promising method to optimize the design and performance of polymer solar cells.

Original languageEnglish
Pages (from-to)690-699
Number of pages10
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume53
Issue number10
DOIs
StatePublished - 15 May 2015

Keywords

  • Gaussian density of state
  • interface layer
  • interfaces
  • modeling
  • open circuit voltage
  • organic solar cell
  • simulations
  • work function

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