Interplay between energetic and kinetic factors on the ambient stability of n-channel organic transistors based on perylene diimide derivatives

Joon Hak Oh, Ya Sen Sun, Rüdiger Schmidt, Michael F. Toney, Dennis Nordlund, Martin Könemann, Frank Würthner, Zhenan Bao

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

The effects of the interplay between energetic and kinetic factors on the air stability of n-channel organic thin-film transistors (OTFTs) were studied using two perylene diimide (PDI) compounds with distinctly different lowest unoccupied molecular orbital (LUMO) levels. On the basis of the empirical energy level windows, one compound (N,N′-bis(2,2,3,3,4,4,5,5,5-nonafluoropentyl) -3,4:9,10-tetracarboxylic acid diimide (PDI-F): -3.84 eV) is at the onset region for air stability, whereas the other (N,N′-bis(cyclohexyl)-1,7-dicyano- perylene-3,4:9,10-tetracarboxylic acid diimide (PDI-CN2): -4.33 eV) is in the air-stable region. Charge-transport behaviors under an inert atmosphere and in air were investigated as a function of active layer thickness. Charge transport in air was greatly affected by the active layer thickness for both compounds, an effect that has been overlooked so far. The ambient stability of the air-unstable PDI-F TFTs increased significantly for thicknesses over ∼10 monolayers (ML). Surprisingly, the previously considered "air-stable" PDI-CN2 TFTs were not stable in air if the active layer thickness was less than ∼4 ML. The molecular packing and orientation of the PDI thin films were investigated using grazing incidence X-ray diffraction (GIXD) and near-edge X-ray absorption fine structure (NEXAFS). We found that the minimum thickness required for air stability is closely related to the LUMO level, film morphology, and film growth mode.

Original languageEnglish
Pages (from-to)5508-5518
Number of pages11
JournalChemistry of Materials
Volume21
Issue number22
DOIs
StatePublished - 24 Nov 2009

Fingerprint

Dive into the research topics of 'Interplay between energetic and kinetic factors on the ambient stability of n-channel organic transistors based on perylene diimide derivatives'. Together they form a unique fingerprint.

Cite this