Investigating charge generation in polymer: non-fullerene acceptor bulk heterojunction films

Dani M. Stoltzfus, Bryon W. Larson, Nasim Zarrabi, Paul E. Shaw, Andrew J. Clulow, Hui Jin, Paul L. Burn, Ian R. Gentle, Nikos Kopidakis

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1 Citation (Scopus)

Abstract

Non-fullerene acceptors are now capable of being used in high efficiency bulk heterojunction (BHJ) donor-acceptor organic solar cells. Acceptors comprising single or multiple linked chromophores have been used. We have developed a new non-fullerene molecular acceptor as well as two non-polymeric macromolecular materials that contain four equivalents of a similar chromophore, but can adopt different spatial arrangements of the chromophores. We compare the effect of having single and multiple chromophores within a macromolecule on the charge generation processes in P3HT:non-fullerene acceptor BHJ films using Transient Absorption Spectroscopy (TAS) and Time Resolved Microwave Conductivity (TRMC) measurements. It was found from the TAS measurements that at low weight percent (5 wt%) the single chromophore formed more polarons than the acceptors in which chromophores were linked, due to it having a more even distribution within the film. At higher concentrations (50 wt%) the trend was reversed due to the single chromophore forming crystalline domains, which reduced the interface area with the P3HT donor. The TRMC measurements showed that more mobile carriers were formed in the macromolecular acceptors when used at low concentrations in the blend and, independent of concentration, mobile carriers had a longer lifetime when compared to films containing the molecular material, which we ascribe to the charges being able to sample more than one chromophore and thus reduce recombination events.

Original languageEnglish
Pages (from-to)177-186
Number of pages10
JournalOrganic Electronics
Volume55
DOIs
Publication statusPublished - 1 Apr 2018
Externally publishedYes

Keywords

  • Charge generation
  • Non-fullerene acceptor
  • Organic photovoltaics
  • Synthesis

Cite this

Stoltzfus, D. M., Larson, B. W., Zarrabi, N., Shaw, P. E., Clulow, A. J., Jin, H., Burn, P. L., Gentle, I. R., & Kopidakis, N. (2018). Investigating charge generation in polymer: non-fullerene acceptor bulk heterojunction films. Organic Electronics, 55, 177-186. https://doi.org/10.1016/j.orgel.2018.01.017