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Efficient Charge Injection in Organic Field‐Effect Transistors Enabled by Low‐Temperature Atomic Layer Deposition of Ultrathin VO x Interlayer
Author(s) -
Gao Yuanhong,
Shao Youdong,
Yan Lijia,
Li Hao,
Su Yantao,
Meng Hong,
Wang Xinwei
Publication year - 2016
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.201600482
Subject(s) - atomic layer deposition , materials science , pentacene , vanadium , contact resistance , optoelectronics , nanotechnology , oxidizing agent , field effect transistor , transistor , thin film , layer (electronics) , thin film transistor , organic chemistry , electrical engineering , engineering , voltage , chemistry , metallurgy
Charge injection at metal/organic interface is a critical issue for organic electronic devices in general as poor charge injection would cause high contact resistance and severely limit the performance of organic devices. In this work, a new approach is presented to enhance the charge injection by using atomic layer deposition (ALD) to prepare an ultrathin vanadium oxide (VO x ) layer as an efficient hole injection interlayer for organic field‐effect transistors (OFETs). Since organic materials are generally delicate, a gentle low‐temperature ALD process is necessary for compatibility. Therefore, a new low‐temperature ALD process is developed for VO x at 50 °C using a highly volatile vanadium precursor of tetrakis(dimethylamino)vanadium and non‐oxidizing water as the oxygen source. The process is able to prepare highly smooth, uniform, and conformal VO x thin films with precise control of film thickness. With this ALD process, it is further demonstrated that the ALD VO x interlayer is able to remarkably reduce the interface contact resistance, and, therefore, significantly enhance the device performance of OFETs. Multiple combinations of the metal/VO x /organic interface (i.e., Cu/VO x /pentacene, Au/VO x /pentacene, and Au/VO x /BOPAnt) are examined, and the results uniformly show the effectiveness of reducing the contact resistance in all cases, which, therefore, highlights the broad promise of this ALD approach for organic devices applications in general.