Efficiency enhancement in organic photovoltaic cells: Consequences of optimizing series resistance

Jonathan D. Servaites, Sina Yeganeh, Tobin J. Marks, Mark A. Ratner

Research output: Contribution to journalArticle

215 Scopus citations

Abstract

Here, means to enhance power conversion efficiency (PCE or η) in bulkheterojunction (BHJ) organic photovoltaic (OPV) cells by optimizing the series resistance (Rs)-also known as the cell internal resistance-are studied. It is shown that current state-of-the-art BHJ OPVs are approaching the limit for which efficiency can be improved via Rs, reduction alone. This evaluation addresses OPVs based on a poly(3-hexylthiophene):6,6-phenyl C61-butyric acid methyl ester (P3HT:PCBM) active layer, as well as future high-efficiency OPVs (η > 10%). A diode-based modeling approach is used to assess changes in Rs. Given that typical published P3HT:PCBM test cells have relatively small areas (∼0.1 cm2), the analysis is extended to consider efficiency losses for larger area cells and shows that the transparent anode conductivity is then the dominant materials parameter affecting Rs efficiency losses. A model is developed that uses cell sizes and anode conductivities to predict current-voltage response as a function of resistive losses. The results show that the losses due to Rs remain minimal until relatively large cell areas (>0.1 cm2) are employed. Finally, Rs effects on a projected high-efficiency OPV scenario are assessed, based on the goal of cell efficiencies >10%. Here, Rs optimization effects remain modest; however, there are now more pronounced losses due to cell size and it is shown how these losses can be mitigated by using higher conductivity anodes.

Original languageEnglish (US)
Pages (from-to)97-104
Number of pages8
JournalAdvanced Functional Materials
Volume20
Issue number1
DOIs
StatePublished - Jan 8 2010

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ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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