TY - JOUR
T1 - Quasi-ordering in spontaneously associated surface dipoles
T2 - An intrinsic interfacial factor for high-k polymer insulated organic field-effect transistors
AU - Xu, Wentao
AU - Wang, Feng
AU - Rhee, Shi Woo
PY - 2012/1/28
Y1 - 2012/1/28
N2 - In this study, we report the observation of quasi-ordering in spontaneously associated highly polar surface functional groups (CN) in the high-k polymer dielectric, cyanoethyl pullulan, and its impact on the organic field-effect transistor (OFET) characteristics. We find that the association originates from CN⋯H-C-CN hydrogen bonding as confirmed by XPS, NEXAFS experiments and molecular simulations. The quasi-ordered surface dipoles preferentially induce vertically well-stacked local semiconductor molecular clusters during the initial deposition process, which then promote large-area layer-by-layer growth. By maintaining sufficient quasi-ordering, high transistor performance (μ ≈ 6.5 cm 2 V -1 s -1, SS ≈ 0.062 V dec -1) is obtained under low driving voltages (-3 to -5 V), while breakup of the association at higher baking temperatures leads to a dramatic drop in μ by a factor of ∼10. Our results demonstrate that local quasi-ordering of polymeric surface dipoles, which has a significant effect on the initial semiconductor molecular growth, represents a novel and sensitive factor affecting OFET characteristics.
AB - In this study, we report the observation of quasi-ordering in spontaneously associated highly polar surface functional groups (CN) in the high-k polymer dielectric, cyanoethyl pullulan, and its impact on the organic field-effect transistor (OFET) characteristics. We find that the association originates from CN⋯H-C-CN hydrogen bonding as confirmed by XPS, NEXAFS experiments and molecular simulations. The quasi-ordered surface dipoles preferentially induce vertically well-stacked local semiconductor molecular clusters during the initial deposition process, which then promote large-area layer-by-layer growth. By maintaining sufficient quasi-ordering, high transistor performance (μ ≈ 6.5 cm 2 V -1 s -1, SS ≈ 0.062 V dec -1) is obtained under low driving voltages (-3 to -5 V), while breakup of the association at higher baking temperatures leads to a dramatic drop in μ by a factor of ∼10. Our results demonstrate that local quasi-ordering of polymeric surface dipoles, which has a significant effect on the initial semiconductor molecular growth, represents a novel and sensitive factor affecting OFET characteristics.
UR - http://www.scopus.com/inward/record.url?scp=84855405679&partnerID=8YFLogxK
U2 - 10.1039/c1jm14398k
DO - 10.1039/c1jm14398k
M3 - Article
AN - SCOPUS:84855405679
SN - 0959-9428
VL - 22
SP - 1482
EP - 1488
JO - Journal of Materials Chemistry
JF - Journal of Materials Chemistry
IS - 4
ER -