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Heterojunction Ambipolar Organic Transistors Fabricated by a Two‐Step Vacuum‐Deposition Process
Author(s) -
Wang J.,
Wang H.,
Yan X.,
Huang H.,
Jin D.,
Shi J.,
Tang Y.,
Yan D.
Publication year - 2006
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.200500111
Subject(s) - ambipolar diffusion , heterojunction , materials science , optoelectronics , layer (electronics) , charge carrier , organic field effect transistor , transistor , homo/lumo , organic semiconductor , deposition (geology) , field effect transistor , nanotechnology , electron , molecule , organic chemistry , electrical engineering , chemistry , paleontology , physics , engineering , quantum mechanics , voltage , sediment , biology
Ambipolar organic field‐effect transistors (OFETs) are produced, based on organic heterojunctions fabricated by a two‐step vacuum‐deposition process. Copper phthalocyanine (CuPc) deposited at a high temperature (250 °C) acts as the first (p‐type component) layer, and hexadecafluorophthalocyaninatocopper (F 16 CuPc) deposited at room temperature (25 °C) acts as the second (n‐type component) layer. A heterojunction with an interpenetrating network is obtained as the active layer for the OFETs. These heterojunction devices display significant ambipolar charge transport with symmetric electron and hole mobilities of the order of 10 –4 cm 2 V –1 s –1 in air. Conductive channels are at the interface between the F 16 CuPc and CuPc domains in the interpenetrating networks. Electrons are transported in the F 16 CuPc regions, and holes in the CuPc regions. The molecular arrangement in the heterojunction is well ordered, resulting in a balance of the two carrier densities responsible for the ambipolar electrical characteristics. The thin‐film morphology of the organic heterojunction with its interpenetrating network structure can be controlled well by the vacuum‐deposition process. The structure of interpenetrating networks is similar to that of the bulk heterojunction used in organic photovoltaic cells, therefore, it may be helpful in understanding the process of charge collection in organic photovoltaic cells.