Printed Organic Light-Emitting Diodes on Fabric with Roll-to-Roll Sputtered ITO Anode and Poly(vinyl alcohol) Planarization Layer

Abstract

Electronic textiles, which are a combination of fabrics and electronics, can help realize wearable electronic devices by changing the rigidity of these textiles. We demonstrate organic light-emitting diodes (OLEDs) by directly printing the emitting material on fabric substrates using the nozzle-printing technique. Printing the emitting material directly on a fabric substrate with a rough surface is difficult. To address this, we introduce a planarization layer by using a synthesized 3.5 wt % poly­(vinyl alcohol) (PVA) solution. The sputtered ITO anode with the thermally annealed PVA planarization layer on a fabric substrate achieves a low sheet resistance in the range of 60–80 Ω/sq, whereas the ITO electrode without a PVA layer exhibits high sheet resistance values of 10–25 kΩ/sq. This result is because the thermally annealed PVA layer on the fabric surface has a uniform surface morphology and a water contact angle as high as 96°, thus acting as a protective layer with a waterproofing effect; in contrast, the water is completely absorbed on the rough surface without a PVA layer. The fabric-based OLEDs with a thermally annealed PVA layer exhibit a lower turn-on voltage of 3 V and higher luminance values of 5346 cd/m2 at 8 V compared with the devices without a PVA layer (7 V and 3622 cd/m2) at 18 V. These fabric-based OLEDs with a PVA planarization layer can be produced by the nozzle-printing process and can achieve selective patterning as well as direct printing of the emitting material and ITO sputtering on a fabric substrate; furthermore, they emit well even when it bent into a circle with a radius of 1 cm.

Internal conversion rate constant calculations considering Duschinsky, anharmonic and Herzberg–Teller effects

“…[13][14][15] The roll-to-roll or ''wet'' tools, printing, spin-coating methods can be an alternative, because they are significantly cheaper and enable the use of luminescent polymers such as polyfluorenes. [16][17][18][19][20][21] Since polyfluorenes have a high fluorescence quantum yield and good thermal stability, OLEDs based on them are expected to be efficient with a long lifetime. [22][23][24] Calculations of molecular photophysical properties can be very useful when designing the molecular structure of semiconducting polymers in OLED devices.…”

Thermally Laminated Lighting Textile for Wearable Displays with High Durability

“…Wearable electronic devices are attracting more and more attention as they can provide personal real-time medical monitoring, communication, entertainment interaction, etc. − Textiles are considered as an ideal platform to integrate electronics for wearable applications due to their lightweight, softness, and comfort. − There have been many studies on fabric/fiber-based electronic devices, including sensors, nanogenerators, heaters, solar cells, batteries, etc. − Light emission is another interesting functionality that can be integrated with textiles for applications in wearable display, fashion design, warning clothing, and light therapy. , So far, various luminescence strategies, such as alternating current electroluminescence (ACEL), organic light-emitting diodes (OLED), − light electrochemical cells (LECs), and side-emitting polymeric optical fibers (POFs) coupled with LEDs, have been developed for fabricating light-emitting devices on fibers or planar fabrics. Stretchability, washability, large display area, and low production cost are the fundamental requirements for light-emitting textiles from a practical standpoint.…”

Recent Progress in Self-Healable Hydrogel-Based Electroluminescent Devices: A Comprehensive Review

“…Dispenza, C. et al [ 148 ] introduced novel nanocomposites of polyaniline (PANI) and obtained functional hydrogels with better transparency and environmental sensitivity. Hydrogels based on PVA also have the capability to be printed on textiles materials [ 149 ], which means PVA-based hydrogels are more compatible for textile substrates. Table 2 summarizes the fabrication, composites and other detailed results of EL devices fabricated from PVA-based hydrogels.…”