Analysis of External and Internal Disorder to Understand Band-Like Transport in n-Type Organic Semiconductors

Marc Antoine Stoeckel, Yoann Olivier, Marco Gobbi, Dmytro Dudenko, Vincent Lemaur, Mohamed Zbiri, Anne A.Y. Guilbert, Gabriele D'Avino, Fabiola Liscio, Andrea Migliori, Luca Ortolani, Nicola Demitri, Xin Jin, Young Gyun Jeong, Andrea Liscio, Marco Vittorio Nardi, Luca Pasquali, Luca Razzari, David Beljonne, Paolo SamorìEmanuele Orgiu

Research output: Contribution to journalArticlepeer-review

Abstract

Charge transport in organic semiconductors is notoriously extremely sensitive to the presence of disorder, both internal and external (i.e., related to interactions with the dielectric layer), especially for n-type materials. Internal dynamic disorder stems from large thermal fluctuations both in intermolecular transfer integrals and (molecular) site energies in weakly interacting van der Waals solids and sources transient localization of the charge carriers. The molecular vibrations that drive transient localization typically operate at low-frequency (<a-few-hundred cm−1), which makes it difficult to assess them experimentally. Hitherto, this has prevented the identification of clear molecular design rules to control and reduce dynamic disorder. In addition, the disorder can also be external, being controlled by the gate insulator dielectric properties. Here a comprehensive study of charge transport in two closely related n-type molecular organic semiconductors using a combination of temperature-dependent inelastic neutron scattering and photoelectron spectroscopy corroborated by electrical measurements, theory, and simulations is reported. Unambiguous evidence that ad hoc molecular design enables the electron charge carriers to be freed from both internal and external disorder to ultimately reach band-like electron transport is provided.

Original languageEnglish
Article number2007870
JournalAdvanced materials
Volume33
Issue number13
Early online date25 Feb 2021
DOIs
Publication statusPublished - 1 Apr 2021

Keywords

  • charge transport
  • disorder
  • field-effect transistors
  • organic semiconductors
  • phonons

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