Doping challenges in organic semiconductors
Date : September 21, 2022 16:00 ~
Speaker : 강기훈 (서울대학교 재료공학부)
Professor : Prof. Dohun Kim, Prof. Sunghoon Jung
Location : 56동105호 +온라인 중계 (코로나 방역 상황에 따라 변동 가능)
Doping has been a key topic in organic electronics since the demonstration of a metallic conductivity in doped p-conjugated polymers. However, it has been difficult to prevent dopant-induced structural and energetic disorder, while maintaining a high conductivity. We have developed an efficient doping method based on solid-state diffusion of 2,3,5,6-tetrafluoro- 7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) which introduced a minimal structural disorder in various conjugated polymers including poly(2,5-bis(3- hexadecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). The doping enabled a consistent observation of both a nearly-ideal Hall effect and a two-dimensional weak-localisation phenomenon in the doped PBTTT, for the first time for conducting polymers, to the best of our knowledge [1]. Furthermore, we have recently employed this doping method to enhance charge injection properties in organic field-effect transistors (FETs) [2, 3]. A selective contact doping of bottom-gated PBTTT FETs by solid-state diffusion of F4-TCNQ achieved a significantly lower contact resistance. Our developed post-doping treatment was shown to be effective for resolving dopant diffusion problem, which is essential for designing stable and low-power organic electronic devices by utilizing doping of conjugated polymers.
References
[1] K. Kang†, S. Watanabe† et al. Nature Materials 15, 896 (2016)
[2] Y. Kim et al. Advanced Materials 31, 1806697 (2019)
[3] Y. Kim et al. Advanced Functional Materials 30, 2000058 (2020).