N-acyl-dithieno[3,2-b2',3'-d]pyrrole-based low bandgap copolymers affording improved open-circuit voltages and efficiencies in polymer solar cells

Jurgen Kesters, Pieter Verstappen, Wouter Vanormelingen, Jeroen Drijkoningen, Tim Vangerven, Dries Devisscher, Lidia Marin, Benoît Champagne, Jean Manca, Laurence Lutsen, Dirk Vanderzande, Wouter Maes

Research output: Contribution to journalArticlepeer-review

Abstract

Three distinct low bandgap copolymers are synthesized by the combination of N-(2′-propylpentanoyl)dithieno[3,2-b:2′,3′-d]pyrrole (DTP) and (fluorinated) 2,3-bis[5′-(2"-ethylhexyl)thiophen-2′-yl]quinoxaline (Qx) and these PDTPQx derivatives are investigated as electron donor materials in bulk heterojunction polymer solar cells. Due to the DTP N-acylation and the introduction of the Qx units, both the open-circuit voltage (Voc) and the short-circuit current density (Jsc) increase compared to previous devices based on DTP-type donor polymers. Organic solar cells with an average Voc of 0.67 V, a Jsc of 12.57 mA/cm2 and a fill factor of 0.54 are obtained, affording a power conversion efficiency of 4.53% (4.81% for the top-performing device),are cord value for(N-acyl-)DTP-based polymer solar cells devoid of special interlayer materials. Despite further enhancement of the Voc, the solar cell efficiency declines for the fluorinated PDTPQx copolymers because of the inability to achieve a finely intermixed bulk hetero junction blend anomorphology.

Original languageEnglish
Pages (from-to)70-77
Number of pages8
JournalSolar Energy Materials and Solar Cells
Volume136
DOIs
Publication statusPublished - 2015

Keywords

  • Dithieno[3,2-b:2′,3′-d]pyrrole
  • Fluorination
  • Low bandgap copolymers
  • N-acylation
  • Organic photovoltaics
  • Quinoxaline

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