Impact of Singly Occupied Molecular Orbital Energy on the n-Doping Efficiency of Benzimidazole Derivatives

Sergi Riera-Galindo, Alessio Orbelli Biroli, Alessandra Forni, Yuttapoom Puttisong, Francesca Tessore, Maddalena Pizzotti, Eleni Pavlopoulou, Eduardo Solano, Suhao Wang, Gang Wang, Tero Petri Ruoko, Weimin M. Chen, Martijn Kemerink, Magnus Berggren, Gabriele Di Carlo, Simone Fabiano

Research output: Contribution to journalArticleScientificpeer-review

24 Citations (Scopus)


We investigated the impact of singly occupied molecular orbital (SOMO) energy on the n-doping efficiency of benzimidazole derivatives. By designing and synthesizing a series of new air-stable benzimidazole-based dopants with different SOMO energy levels, we demonstrated that an increase of the dopant SOMO energy by only &tild;0.3 eV enhances the electrical conductivity of a benchmark electron-transporting naphthalenediimide-bithiophene polymer by more than 1 order of magnitude. By combining electrical, X-ray diffraction, and electron paramagnetic resonance measurements with density functional theory calculations and analytical transport simulations, we quantitatively characterized the conductivity, Seebeck coefficient, spin density, and crystallinity of the doped polymer as a function of the dopant SOMO energy. Our findings strongly indicate that charge and energy transport are dominated by the (relative) position of the SOMO level, whereas morphological differences appear to play a lesser role. These results set molecular-design guidelines for next-generation n-type dopants.

Original languageEnglish
Pages (from-to)37981-37990
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number41
Publication statusPublished - 16 Oct 2019
Externally publishedYes
Publication typeA1 Journal article-refereed


  • DMBI
  • electron transfer
  • n-doped polymers
  • n-type dopants
  • SOMO energy

ASJC Scopus subject areas

  • Materials Science(all)


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