Printed thin-film transistors with functionalized single-walled carbon nanotube inks

A simple and scalable method to print high performance thin-film transistors (TFTs) with high yield by an aerosol jet printer has been developed, using water-based and chemically functionalized singlewalled carbon nanotube (SCNT) inks as the semiconducting layer. The absorption spectra, Raman spectra and photoluminescence excitation (PLE) spectra of the SCNT ink indicated that metallic species and small diameter semiconducting species in CoMoCat 76 were effectively eliminated after reaction with 2,2-azobisisobutyronitrile (AIBN) in dimethyformamide (DMF). The functionalized SCNTs were dispersed in 1% SDS aqueous solution, and the as-prepared SCNTs inks were directly used to print TFTs using an aerosol jet printing system without any additional purification. Printed TFTs with high yield were obtained by tuning the concentrations of SCNTs and surfactants in the inks. The printed side-gate and bottom-gate TFTs exhibited the effective mobility of 1 cm2 V 1 s 1 and an on/off ratio over 103. In addition, these printed TFTs were hysteresis-free and able to operate at lowvoltage when using printable high-capacitance ion gel as the dielectric layer. The new method has opened the route to fabricate all-printed SCNT TFTs on flexible substrate with high performance

Low-temperature laser sintering of printed nano-silver electrodes for flexible electronics

In this paper, we demonstrated the continuous wave (CW,1064nm) laser sintering of nano-sliver electrode patterns printed by an aerosol jet printer on polyethylene terephthalate (PET) substrate. A laser sintering apparatus has been constructued which has precise control of laser spot size to 15um and can effectively minimize the damage of substrates and other functional layer in multilayer devices. The effects of the laser processing parameter on the sintering results including scanning speed and power were investigated. The electrical resistivity of laser sintered nano-silver electrode was measured to be 2.4 &times; 10^{<font size="2">-6</font>}&Omega;m which is similar to that achieved in conventional oven sintering

Gravure Printed Network Based on Silver Nanowire for Transparent Electrode

Silver nanowires were gravure printed on flexbile Poly(ethylene terephthalate) film to form conductive transparent patterns. Suspensions containing silver nanowires with different concentrations were formulated and various cell parameters in grauvre plate were investigated in the printing experiments. Printed samples were characterized by microscope and probes for their optical and electrical properties. It was found that concentration and uniformity of the Ag NW network play key roles in the optical transmission and electrical conductivity of printed films. Experimental result showed that with optimized parameters the transmission of 89% at sheet resistance of 200 &Omega;/sq have been achieved in the gravure printed transparent conductive films

Embedded Ag/Ni Metal-Mesh with Low Surface Roughness As Transparent Conductive Electrode for Optoelectronic Applications

Metal-mesh is one of the contenders to replace indium tin oxide (ITO) as transparent conductive electrodes (TCEs) for optoelectronic applications. However, considerable surface roughness accompanying metal-mesh type of transparent electrodes has been the root cause of electrical short-circuiting for optoelectronic devices, such as organic light-emitting diode (OLED) and organic photovoltaic (OPV). In this work, a novel approach to making metal-mesh TCE has been proposed that is based on hybrid printing of silver (Ag) nanoparticle ink and electroplating of nickel (Ni). By polishing back the electroplated Ni, an extremely smooth surface was achieved. The fabricated Ag/Ni metal-mesh TCE has a surface roughness of 0.17 nm, a low sheet resistance of 2.1 Ω/□, and a high transmittance of 88.6%. The figure of merit is 1450, which is 30 times better than ITO. In addition, the Ag/Ni metal-mesh TCE shows outstanding mechanical flexibility and environmental stability at high temperature and humidity. Using the polished Ag/Ni metal-mesh TCE, a flexible quantum dot light-emitting diode (QLED) was fabricated with an efficiency of 10.4 cd/A and 3.2 lm/W at 1000 cd/m²

Hybrid Printing Metal-mesh Transparent Conductive Films with Lower Energy Photonically Sintered Copper/tin Ink

Abstract With the help of photonic sintering using intensive pulse light (IPL), copper has started to replace silver as a printable conductive material for printing electrodes in electronic circuits. However, to sinter copper ink, high energy IPL has to be used, which often causes electrode destruction, due to unreleased stress concentration and massive heat generated. In this study, a Cu/Sn hybrid ink has been developed by mixing Cu and Sn particles. The hybrid ink requires lower sintering energy than normal copper ink and has been successfully employed in a hybrid printing process to make metal-mesh transparent conductive films (TCFs). The sintering energy of Cu/Sn hybrid films with the mass ratio of 2:1 and 1:1 (Cu:Sn) were decreased by 21% compared to sintering pure Cu film, which is attributed to the lower melting point of Sn for hybrid ink. Detailed study showed that the Sn particles were effectively fused among Cu particles and formed conducting path between them. The hybrid printed Cu/Sn metal-mesh TCF with line width of 3.5 μm, high transmittance of 84% and low sheet resistance of 14 Ω/□ have been achieved with less defects and better quality than printed pure copper metal-mesh TCFs

Fabrication and electrical properties of all-printed carbon nanotube thin film transistors on flexible substrates

In this manuscript, we developed a high-performance, printable and water-based semiconducting SCNT ink, and fabricated all printed chemically functionalized CoMoCat 76 SCNT thin film transistors (TFTs) on flexible substrates via a suite of printing technologies. The metallic species in the pristine CoMoCat 76 SCNTs were effectively eliminated by organic radicals, and the functionalized SCNTs were characterized by UV-Vis-NIR spectroscopy and Raman spectra. The high quality, printable and water-based functionalized SCNT inks were obtained by tuning the ink ingredients, such as the concentrations of surfactants and additives. The printing methods we investigated include inkjet printing, aerosol jet printing and a hybrid with nanoimprinting. Large area source and drain electrode patterns were first fabricated on flexible substrates by a hybrid printing method, and then the optimal SCNT ink was printed on the channel of the TFT devices by ink-jet printing. Subsequently, the silver side-gate electrode and ion gel dielectric layer were deposited by aerosol jet printing. The all-printed flexible TFTs exhibited an effective mobility up to 1.5 cm2 V 1 s1 and an on/off ratio up to 4 103. This work opens up a way to fabricate scalable and all-printed flexible electronics, and it is of benefit to generalize the practical applications of flexible electronics in the future