Nanoscale phase domain structure and associated device performance of organic solar cells based on a diketopyrrolopyrrole polymer

Evan L. Williams, Sergey Gorelik, Inyee Phang, Michel Bosman, Chellappan Vijila, Gomathy Sandhya Subramanian, Prashant Sonar, Jonathan Hobley, Samarendra P. Singh, Hiroyuki Matsuzaki, Akihiro Furube, Ryuzi Katoh

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

We investigate the blend morphology and performance of bulk heterojunction organic photovoltaic devices comprising the donor polymer, pDPP-TNT (poly{3,6-dithiophene-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1, 4-dione-alt-naphthalene}) and the fullerene acceptor, [70]PCBM ([6,6]-phenyl C71-butyric acid methyl ester). The blend morphology is heavily dependent upon the solvent system used in the fabrication of thin films. Thin films spin-coated from chloroform possess a cobblestone-like morphology, consisting of thick, round-shaped [70]PCBM-rich mounds separated by thin polymer-rich valleys. The size of the [70]PCBM domains is found to depend on the overall film thickness. Thin films spin-coated from a chloroform:dichlorobenzene mixed solvent system are smooth and consist of a network of pDPP-TNT nanofibers embedded in a [70]PCBM-rich matrix. Rinsing the films in hexane selectively removes [70]PCBM and allows for analysis of domain size and purity. It also provides a means for investigating exciton dissociation efficiency through relative photoluminescence yield measurements. Devices fabricated from chloroform solutions show much poorer performance than the devices fabricated from the mixed solvent system; this disparity in performance is seen to be more pronounced with increasing film thickness. The primary cause for the improved performance of devices fabricated from mixed solvents is attributed to the greater donor-acceptor interfacial area and resulting greater capacity for charge carrier generation.

Original languageEnglish
Pages (from-to)20113-20124
Number of pages12
JournalRSC Advances
Volume3
Issue number43
DOIs
Publication statusPublished - 2013 Nov 21

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

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