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Effect of Gate Electrode Work‐Function on Source Charge Injection in Electrolyte‐Gated Organic Field‐Effect Transistors
Author(s) -
Fabiano Simone,
Braun Slawomir,
Fahlman Mats,
Crispin Xavier,
Berggren Magnus
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201302070
Subject(s) - materials science , electrolyte , work function , contact resistance , electrode , optoelectronics , transistor , field effect transistor , semiconductor , organic semiconductor , nanotechnology , voltage , electrical engineering , chemistry , layer (electronics) , engineering
Systematic investigation of the contact resistance in electrolyte‐gated organic field‐effect transistors (OFETs) demonstrates a dependence of source charge injection versus gate electrode work function. This analysis reveals contact‐limitations at the source metal‐semiconductor interface and shows that the contact resistance increases as low work function metals are used as the gate electrode. These findings are attributed to the establishment of a built‐in potential that is high enough to prevent the Fermi‐level pinning at the metal‐organic interface. This results in an unfavorable energetic alignment of the source electrode with the valence band of the organic semiconductor. Since the operating voltage in the electrolyte‐gated devices is on the same order as the variation of the work functions, it is possible to tune the contact resistance over more than one order of magnitude by varying the gate metal.