Substrate-embedded metal meshes for ITO-free organic light emitting diodes.

Organic light-emitting diodes (OLEDs) have great potential for use in large-area display and lighting applications, but their widespread adoption for large areas is hindered by the high cost and insufficient performance of indium tin oxide (ITO) anodes. In this study, we introduce an alternative anode material - a silver mesh embedded in glass - to facilitate production of large-area OLEDs. We present a facile, scalable manufacturing technique to create high aspect ratio micromeshes embedded in glass to provide the planar geometry needed for OLED layers. Our phosphorescent green OLEDs achieve a current efficiency of 51.4 cd/A at 1000 cd/m2 and reach a slightly higher external quantum efficiency compared to a standard ITO/glass reference sample. Notably, these advancements are achieved without any impact on the viewing angle of the OLEDs. These findings represent a promising advancement towards ITO-free, high-efficiency OLEDs for various high performance, large-area applications, such as lighting and displays.

Graphene and Poly(3,4-ethylene dioxythiophene):Poly(4-styrenesulfonate) on Nonwoven Fabric as a Room Temperature Metal and Its Application as Dry Electrodes for Electrocardiography.

Highly conductive, metal-like poly(ethylene terephthalate) (PET) nonwoven fabric was prepared by coating poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) containing dimethyl sulfoxide (DMSO) onto PET nonwoven fabric previously coated with graphene/graphite. The sheet resistance of the original nonwoven fabric decreases from >80 MΩ□-1 to 1.1 Ω□-1 after coating with 10.7 wt % graphene and 5.48 wt % PEDOT:PSS with a maximum current at breakdown of 4 A. This sheet resistance is lower than previously reported sheet resistances of fabrics coated with graphene films, PEDOT:PSS films, or PEDOT:PSS coated fabrics from the literature. The effect of temperature on the resistance of graphene/PEDOT:PSS coated fabric has revealed that the resistance decreases with increasing temperature, analogous to semiconductors, with a clear semiconductor-metal transition occurring at 290 K. Finally, a coating of 18 wt % graphene/graphite and 2.5 wt % PEDOT:PSS (Rs = 5.5 Ω□-1) screen printed on the nonwoven fabric was shown to function as an electrode for electrocardiography without any hydrogel and with dry skin conditions. This composite coating finds application in wearable electronics for military and consumer sectors.

Screen-Printed PEDOT:PSS Electrodes on Commercial Finished Textiles for Electrocardiography.

Electrocardiography (ECG) is an essential technique for analyzing and monitoring cardiovascular physiological conditions such as arrhythmia. This article demonstrates the integration of screen-printed ECG circuitry from a commercially available conducting polymer, PEDOT:PSS, onto commercially available finished textiles. ECG signals were recorded in dry skin conditions due to the ability of PEDOT:PSS to function as both ionic and electronic conductors. The signal amplifies when the skin transpires water vapor or by applying a common lotion on the skin. Finally, PEDOT:PSS wires connected to PEDOT:PSS electrodes have been shown to record ECG signals comparable to Ag/AgCl connected to copper wires.

PEDOT:PSS "Wires" Printed on Textile for Wearable Electronics.

Herein, the fabrication of all-organic conductive wires is demonstrated by utilizing patterning techniques such as inkjet printing and sponge stencil to apply poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) onto nonwoven polyethylene terephthalate (PET) fabric. The coating of the conducting polymer is only present on the surface of the substrate (penetration depth ∼ 200 µm) to retain the functionality and wearability of the textile. The wires fabricated by different patterning techniques provide a wide range of resistance, i.e., tens of kΩ/□ to less than 2 Ω/□ that allows the resistance to be tailored to a specific application. The sheet resistance is measured to be as low as 1.6 Ω/□, and the breakdown current is as high as 0.37 A for a 1 mm wide line. The specific breakdown current exceeds the previously reported values of macroscopic carbon nanotube based materials. Simple circuits composed of the printed wires are demonstrated, and resistance of the circuit from the measurement agrees with the calculated value based on Kirchhoff's rules. Additionally, the printed PEDOT:PSS wires show less than 6.2% change in sheet resistance after three washing and drying cycles using detergent.