Grain Boundary Induced Bias Instability in Soluble Acene-Based Thin-Film Transistors.
Since the grain boundaries (GBs) within the semiconductor layer of organic field-effect transistors (OFETs) have a strong influence on device performance, a substantial number of studies have been devoted to controlling the crystallization characteristics of organic semiconductors. We studied the intrinsic effects of GBs within 5,11-bis(triethylsilylethynyl) anthradithiophene (TES-ADT) thin films on the electrical properties of OFETs. The GB density was easily changed by controlling nulceation event in TES-ADT thin films. When the mixing time was increased, the number of aggregates in as-spun TES-ADT thin films were increased and subsequent exposure of the films to 1,2-dichloroethane vapor led to a significant increase in the number of nuleation sites, thereby increasing the GB density of TES-ADT spherulites. The density of GBs strongly influences the angular spread and crystallographic orientation of TES-ADT spherulites. Accordingly, the FETs with higher GB densities showed much poorer electrical characteristics than devices with lower GB density. Especially, GBs provide charge trapping sites which are responsible for bias-stress driven electrical instability. Dielectric surface treatment with a polystyrene brush layer clarified the GB-induced charge trapping by reducing charge trapping at the semiconductor-dielectric interface. Our study provides an understanding on GB induced bias instability for the development of high performance OFETs.
Department of Organic and Nano System Engineering, Konkuk University, Seoul 05029, Korea.
Ky V
KV
Nguyen
Department of Chemistry, University of Kentucky, Lexington 40506, USA.
Marcia M
MM
Payne
Department of Chemistry, University of Kentucky, Lexington 40506, USA.
John E
JE
Anthony
Department of Organic and Nano System Engineering, Konkuk University, Seoul 05029, Korea.
Jung Hun
JH
Lee
Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea.
Eunjoo
E
Song
Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea.
Boseok
B
Kang
Department of Chemical Engineering, Pohang University of Science and Technology, Pohang 37673, Korea.
Kilwon
K
Cho
Department of Organic and Nano System Engineering, Konkuk University, Seoul 05029, Korea.
Wi Hyoung
WH
Lee