Origin of enhanced hole injection in inverted organic devices with electron accepting interlayer

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal

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Author(s)

Detail(s)

Original languageEnglish
Pages (from-to)3261-3266
Journal / PublicationAdvanced Functional Materials
Volume22
Issue number15
Publication statusPublished - 7 Aug 2012
Externally publishedYes

Abstract

Conventional organic light emitting devices have a bottom buffer interlayer placed underneath the hole transporting layer (HTL) to improve hole injection from the indium tin oxide (ITO) electrode. In this work, a substantial enhancement in hole injection efficiency is demonstrated when an electron accepting interlayer is evaporated on top of the HTL in an inverted device along with a top hole injection anode compared with the conventional device with a bottom hole injection anode. Current-voltage and space-charge-limited dark injection (DI-SCLC) measurements were used to characterize the conventional and inverted N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'biphenyl)-4,4'diamine (NPB) hole-only devices with either molybdenum trioxide (MoO 3) or 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN) as the interlayer. Both normal and inverted devices with HAT-CN showed significantly higher injection efficiencies compared to similar devices with MoO 3, with the inverted device with HAT-CN as the interlayer showing a hole injection efficiency close to 100%. The results from doping NPB with MoO 3 or HAT-CN confirmed that the injection efficiency enhancements in the inverted devices were due to the enhanced charge transfer at the electron acceptor/NPB interface. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Research Area(s)

  • charge injection, inverted, organic electronics

Citation Format(s)

Origin of enhanced hole injection in inverted organic devices with electron accepting interlayer. / Small, Cephas E.; Tsang, Sai-Wing; Kido, Junji; So, Shu Kong; So, Franky.

In: Advanced Functional Materials, Vol. 22, No. 15, 07.08.2012, p. 3261-3266.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journal