Organic semiconductors (OSCs) have been widely studied due to their merits such as mechanical flexibility, solution processability, and large-area fabrication. However, OSC devices still have to overcome contact resistance issues for better performances. Because of the Schottky contact at the metal–OSC interfaces, a non-ideal transfer curve feature often appears in the low-drain voltage region. To improve the contact properties of OSCs, there have been several methods reported, including interface treatment by self-assembled monolayers and introducing charge injection layers. Here, a selective contact doping of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) by solid-state diffusion in poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT) to enhance carrier injection in bottom-gate PBTTT organic field-effect transistors (OFETs) is demonstrated. Furthermore, the effect of post-doping treatment on diffusion of F4-TCNQ molecules in order to improve the device stability is investigated. In addition, the application of the doping technique to the low-voltage operation of PBTTT OFETs with high-k gate dielectrics demonstrated a potential for designing scalable and low-power organic devices by utilizing doping of conjugated polymers.
Bibliographical noteFunding Information:
This work was supported by the National Creative Research Laboratory Program (grant No. 2012026372) through the National Research Foundation of Korea funded by the Korean Ministry of Science and ICT. S.C. appreciates the financial support from the Korean Ministry of Trade, Industry & Energy and Korea Display Research Consortium support program (10051541). Y.H. appreciates the financial support from the R&D Convergence Program of NST (National Research Council of Science & Technology) of Korea (CAP-15-04-KITECH). D.H. would like to thank the Doctoral Training Centre in Plastic Electronics EP/G037515/1. H.S. acknowledges funding from the European Research Council (ERC) through a Synergy Grant (Grant No. 610116). The authors thank R. D. Pietro for valuable discussions.
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All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering