Solution-processed barium salts as charge injection layers for high performance N-channel organic field-effect transistors

Nam Koo Kim, Dongyoon Khim, Yong Xu, Seung Hoon Lee, Minji Kang, Jihong Kim, Antonio Facchetti, Yong Young Noh*, Dong Yu Kim

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


N-channel organic field-effect transistors (OFETs) have generally shown lower field-effect mobilities (μFET) than their p-type counterparts. One of the reasons is the energetic misalignment between the work function (WF) of commonly used charge injection electrode, i.e. gold (Au), and the lowest unoccupied molecular orbital (LUMO) of n-channel electron- transporting organic semiconductors. Here, we report barium salts as solution-processed interlayers, to improve the electron-injection and/or hole-blocking in top-gate/bottom-contact n-channel OFETs, based on poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl] -alt-5,5'-(2,2'-dithiophene)} (P(NDI2OD-T2)) and phenyl-C61-butyric acid methyl ester (PC61BM). Two different barium salts, barium hydroxide (Ba(OH)2) and barium chloride (Ba(Cl)2), are employed as the ultrathin interlayer (∼2 nm); and they effectively tune the WF of Au from 4.9 eV, to as low as 3.5 eV. The resulting n-channel OFETs exhibit significantly improved μFET, approaching 2.6 cm2/(V s) and 0.1 cm2/(V s) for the best P(NDI2OD-T2) and PC61BM devices, respectively, with Ba(OH)2 as interlayer.

Original languageEnglish (US)
Pages (from-to)9614-9621
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number12
StatePublished - Jun 25 2014


  • barium salts
  • charge injection
  • interlayer
  • organic field-effect transistor
  • work function

ASJC Scopus subject areas

  • General Materials Science


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