Organic Field-Effect Transistors with Bottlebrush Polymer Gate Dielectrics Thermally Cross-Linked in Less Than 1 min

Abstract

We report high-performance and air-stable organic field-effect transistors (OFETs) fabricated with thermally cross-linked bottlebrush polymers as gate dielectrics. By synthesizing bottlebrush polymers with a varying degree of polymerization, we investigate the effect of the density of alkyne functional groups on the on-set cross-linking time (t(c)) and dielectric properties of the bottlebrush polymer thin films. The bottlebrush polymer with the highest density of alkyne groups shows the lowest t(c) of 0.6 min, and t(c) values increase to 0.8, 1, and 30 min as the density of alkyne groups decreases. These t(c) values are unambiguously shorter than that (t(c) > 120 min) of the most widely used polymer gate dielectric, poly(methyl methacrylate) (PMMA). The top-gate/bottom-contact OFET fabricated with poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} and the bottlebrush polymer gate dielectric cross-linked in 1 min shows the highest charge carrier mobility (mu = 0.16 cm(2) V-1 s(-1)) and extended device lifetime (120 h) compared to those of OFETs fabricated with the other bottlebrush polymers and PMMA gate dielectrics. Considering the sufficiently reduced t(c) (<= 1 min) and excellent device properties of bottlebrush polymers, these results demonstrate that thermally cross-linkable bottlebrush polymers without any cross-linking agents would be promising materials for developing high-performance and reliable OFETs fabricated by a high-throughput fabrication method.