Solution-Prepared Hybrid-Nanoparticle Dielectrics for High-Performance Low-Voltage Organic Thin-Film Transistors

Oleic acid capped barium strontium titanate (OA-BST) nanoparticles were synthesized for solution-prepared dielectrics in organic thin-film transistors (OTFTs). The as-synthesized nanoparticles were well-dispersed in organic solvents to deposit very homogeneous dielectric films by direct spin coating. Bottom-gate pentacene TFTs fabricated using these nanoparticle dielectric films showed high mobilities of 1-2 cm(2) V(-1) s(-1) with on/off ratios of 10(3) under a low driven voltage of -2.5 V. Top-gate poly(3,3'''-didodecylquaterthiophene) (PQT-12) TFTs with nanoparticle dielectrics also exhibited a low-voltage operation (-5 V) performance with mobilities of 0.01-0.1 cm(2) V(-1) s(-1) and on/off ratios of 10(3)-10(4). Detailed studies on the gate voltage-dependent mobility of the devices showed that only a low gate electric field needed to achieve the saturated mobility for the OA-BST-based pentacene OTFTs could be attributed to the low trapped-state densities (<3.9 x 10(11) cm(-2)) at the dielectric/semiconductor interfaces for these devices.