Dichotomy between the band and hopping transport in organic crystals: insights from experiments


Yavuz I.

PHYSICAL CHEMISTRY CHEMICAL PHYSICS, cilt.19, sa.38, ss.25819-25828, 2017 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 19 Sayı: 38
  • Basım Tarihi: 2017
  • Doi Numarası: 10.1039/c7cp05297a
  • Dergi Adı: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.25819-25828
  • Marmara Üniversitesi Adresli: Evet

Özet

The molecular understanding of charge-transport in organic crystals has often been tangled with identifying the true dynamical origin. While in two distinct cases where complete delocalization and localization of charge-carriers are associated with band-like and hopping-like transports, respectively, their possible coalescence poses some mystery. Moreover, the existing models are still controversial at ambient temperatures. Here, we review the issues in charge-transport theories of organic materials and then provide an overview of prominent transport models. We explored similar to 60 organic crystals, the single-crystal hole/electron mobilities of which have been predicted by band-like and hopping-like transport models, separately. Our comparative results show that at room-temperature neither of the models are exclusively capable of accurately predicting mobilities in a very broad range. Hopping-like models well-predict experimental mobilities around mu similar to 1 cm(2) V-1 s(-1) but systematically diverge at high mobilities. Similarly, band-like models are good at mu > similar to 50 cm(2) V-1 s(-1) but systematically diverge at lower mobilities. These results suggest the development of a unique and robust room-temperature transport model incorporating a mixture of these two extreme cases, whose relative importance is associated with their predominant regions. We deduce that while band models are beneficial for rationally designing high mobility organic-semiconductors, hopping models are good to elucidate the charge-transport of most organic-semiconductors.