Ladder-Type Silsesquioxane Copolymer Gate Dielectrics for High-Performance Organic Transistors and Inverters

Abstract

A ladder-type poly­(phenyl-co-methacryl silsesquioxane) (PPMSQ) copolymer was developed for use as a gate dielectric in high-performance organic field-effect transistors (OFETs). The ladder-type PPMSQ copolymer was synthesized via the hydrolysis of two types of monomers, methacryloxypropyltrimethoxysilane and phenyltrimethoxysilane, followed by a condensation polymerization. The phenyl groups in one monomer were introduced to enhance the structural ordering of the overlying organic semiconductors, whereas the methacryloxypropyl groups in the other monomer were introduced to cross-link the polymer chains via thermal- or photocuring. The curing process enhanced the electrical strength of the gate dielectric layer due to the formation of a network structure with a reduced free volume. Thermal curing reduced the surface energy of the gate dielectrics, which improved the structural order of the overlying organic semiconductors and promoted the formation of large grains. The ladder-type PPMSQ was used as a gate dielectric to produce benchmark p- and n-channel OFETs based on pentacene and N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8), respectively. The resulting OFETs exhibited excellent electrical performances, including a high carrier mobility (0.53 cm2 V–1 s–1 for the p-type pentacene OFET and 0.17 cm2 V–1 s–1 for the n-type PTCDI-C8 OFET) and a high ON/OFF current ratio exceeding 104. The photocured patterned PPMSQ film was successfully used to fabricate complementary OFET-based inverters that yielded high gains. The use of the ladder-type PPMSQ gate dielectrics provides a novel approach to realizing next-generation organic electronics.

SiO2/Ladder-Like Polysilsesquioxanes Nanocomposite Coatings: Playing with the Hybrid Interface for Tuning Thermal Properties and Wettability

“…Finally, it has to be pointed out that contact angle measurements confirm that particle-loaded coatings can still be considered smooth, from a wetting perspective, since neither a Wenzel state (i.e., significant increase in contact angle hysteresis) nor a Cassie-Baxter state (i.e., superhydrophobic wetting state) are observed. This result is not unexpected, since silsesquioxane-based polymer nanocomposites display smooth surfaces in general [71,72].…”

A Ladder-Type Organosilicate Copolymer Gate Dielectric Materials for Organic Thin-Film Transistors

“…The reported dielectric films formed at a curing temperature of 200 • C exhibited a leakage current density as low as 6 × 10 −9 A·cm −2 at 1 MV·cm −1 [45]. Similarly, Kim et al reported dielectric materials based on a silsesquioxane derivative containing cage-structured epoxy groups, and the resulting films showed a leakage current density of ≈10 −8 A·cm −2 at 1 MV·cm −1 [46].…”

“…To this end, many studies on the development and application of new dielectric materials with low leakage current, high dielectric constant, and facile process have been reported [39][40][41][42][43][44][45][46][47][48]. Among them, organic-inorganic hybrid dielectrics might synergistically combine the advantages of both materials, i.e., the excellent mechanical and electrical properties of inorganics and the flexibility and large area solution processibility of organics [41][42][43][44].…”

“…One of the representative examples is organosilicate materials, a type of silica containing organic groups. A few studies employing dielectric materials containing organosilicates have been reported for the fabrication of OTFTs [45][46][47][48].…”

Intense-pulsed-UV-converted perhydropolysilazane gate dielectrics for organic field-effect transistors and logic gates

“…Several research groups have fabricated the SiO 2 layer by conversion of spin-on-glass (SOG) materials such as perhydropolysilazane (PHPS), silsesquioxane, tetraethyl orthosilicate, and tetramethyl orthosilicate. [20][21][22][23][24] Because of the low cost, simplicity, and excellent substrate adaptability of this approach, this process can replace the conventional vapor deposition process. PHPS, used in this study, is one of the most widely used SOG materials because of its low carbon contamination and ability to form dense lms.…”