An Efficient, “Burn in” Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor

Hyojung Cha, Jiaying Wu, Andrew Wadsworth, Jade Nagitta, Saurav Limbu, Sebastian Pont, Zhe Li, Justin Searle, Mark F. Wyatt, Derya Baran, Ji Seon Kim, Iain McCulloch, James R. Durrant*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

144 Scopus citations

Abstract

A comparison of the efficiency, stability, and photophysics of organic solar cells employing poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3′″-di(2-octyldodecyl)-2,2′;5′,2″;5″,2′″-quaterthiophen-5,5′″-diyl)] (PffBT4T-2OD) as a donor polymer blended with either the nonfullerene acceptor EH-IDTBR or the fullerene derivative, [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) as electron acceptors is reported. Inverted PffBT4T-2OD:EH-IDTBR blend solar cell fabricated without any processing additive achieves power conversion efficiencies (PCEs) of 9.5 ± 0.2%. The devices exhibit a high open circuit voltage of 1.08 ± 0.01 V, attributed to the high lowest unoccupied molecular orbital (LUMO) level of EH-IDTBR. Photoluminescence quenching and transient absorption data are employed to elucidate the ultrafast kinetics and efficiencies of charge separation in both blends, with PffBT4T-2OD exciton diffusion kinetics within polymer domains, and geminate recombination losses following exciton separation being identified as key factors determining the efficiency of photocurrent generation. Remarkably, while encapsulated PffBT4T-2OD:PC71BM solar cells show significant efficiency loss under simulated solar irradiation (“burn in” degradation) due to the trap-assisted recombination through increased photoinduced trap states, PffBT4T-2OD:EH-IDTBR solar cell shows negligible burn in efficiency loss. Furthermore, PffBT4T-2OD:EH-IDTBR solar cells are found to be substantially more stable under 85 °C thermal stress than PffBT4T-2OD:PC71BM devices.

Original languageEnglish (US)
Article number1701156
JournalAdvanced Materials
Volume29
Issue number33
DOIs
StatePublished - Sep 6 2017

Keywords

  • charge separation
  • nonfullerene acceptors
  • organic solar cells
  • trap assisted recombination

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

Fingerprint

Dive into the research topics of 'An Efficient, “Burn in” Free Organic Solar Cell Employing a Nonfullerene Electron Acceptor'. Together they form a unique fingerprint.

Cite this