Solution Processable High Dielectric Constant Nanocomposites Based on ZrO₂ Nanoparticles for Flexible Organic Transistors

Abstract

A solution-based strategy for fabrication of high dielectric constant (κ) nanocomposites for flexible organic field effect transistors (OFETs) has been developed. The nanocomposite was composed of a high-κ polymer, cyanoethyl pullulan (CYELP), and a high-κ nanoparticle, zirconium dioxide (ZrO2). Organic field effect transistors (OFETs) based on neat CYELP exhibited anomalous behavior during device operation, such as large hysteresis and variable threshold voltages, which yielded inconsistent devices and poor electrical characteristics. To improve the stability of the OFET, we introduced ZrO2 nanoparticles that bind with residual functional groups on the high-κ polymer, which reduces the number of charge trapping sites. The nanoparticles, which serve as physical cross-links, reduce the hysteresis without decreasing the dielectric constant. The dielectric constant of the nanocomposites was tuned over the range of 15.6-21 by varying the ratio of the two components in the composite dielectrics, resulting in a high areal capacitance between 51 and 74 nF cm(-2) at 100 kHz and good insulating properties of a low leakage current of 1.8 × 10(-6) A cm(-2) at an applied voltage of -3.5 V (0.25 MV cm(-1)). Bottom-gate, top-contact (BGTC) low operating voltage p-channel OFETs using these solution processable high-κ nanocomposites were fabricated by a contact film transfer (CFT) technique with poly(3-hexylthiophene) (P3HT) as the charge transport layer. Field effect mobilities as high as 0.08 cm(2) V(-1) s(-1) and on/off current ratio of 1.2 × 10(3) for P3HT were measured for devices using the high-κ dielectric ZrO2 nanocomposite. These materials are promising for generating solution coatable dielectrics for low cost, large area, low operating voltage flexible transistors.

Nanoparticles of Cu2ZnSnS4as performance enhancing additives for organic field-effect transistors

“…Reports on applications of inorganic nanoparticles in OFETs are sparse in the literature and have been limited mainly to their use as nanocomposites in gate dielectric layers. [29][30][31] Zinc oxide nanoparticles have been used in polyfluorene composites for lightemitting field effect transistors, 32 whilst Q-ZnO has been applied as a component in a hybrid OFET bilayer device fabricated with P3HT as the organic film. 33 Blends of P3HT and CdSe have been studied in OFETs 34 and also in organic photovoltaics devices.…”

Renewable polymeric materials for electronic applications

“…[75][76][77][78] For example, a pentacene-based organic field-effect transistor with a crosslinked cyanoethyl pullulan dielectric layer was found to operate under a low gate voltage of − 3 V with a remarkably high mobility of~8.62 cm 2 V − 1 s − 1 , an on/off current ratio of~10 5 , and a steep sub-threshold slope of 0.099 V per dec. 75 Furthermore, Beaulieu and co-workers added ZrO 2 nanoparticles to neat cyanoethyl pullulan as physical crosslinks to eliminate the charge-trapping effect and improve the stability and performance of the P3HT transistor devices. 77 In addition to functionalized pullulan, Petritz et al 78 demonstrated the use of trimethylsilyl cellulose as an organic/inorganic bilayer gate dielectric for organic field-effect transistors and complementary inverters, as shown in Figure 13. Using this bilayer dielectric, the fabricated pentacene-and C 60 Charge-trapping electrets in organic field-effect transistor memory As mentioned, using modified cellulose as the dielectric layer in transistor devices results in a different device performance because the concentration of the induced charge carrier at the dielectric/ semiconductor interface is very different from traditional dielectrics.…”

Ultrathin Supported Lipid Monolayer with Unprecedented Mechanical and Dielectric Properties

“…Moreover for low power operations in TFT it is meaningful to maintain the dielectric thickness as thin as possible . To this aim, nanodielectrics such as nanoparticles or self‐assembled monolayers or multilayers have been recently developed and implemented in OFETs . Another class of material, the supported lipid layers, with thicknesses of a few nanometers also constitutes good candidates.…”