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Friday, 17 Nov 2017

Flexible polymer threads set to light up clothing

The fabrication processes used to create the PLEC fibres are relatively simple and inexpensive and lend themselves to scaling-up

23 Mar 2015 | Editor

Huisheng Peng, of Fudan University in Shanghai, and colleagues have published a paper that describes how the researchers created a fibre of a polymer light-emitting electrochemical cell (PLEC) by taking a stainless steel wire and dip-coating it with a thin layer of zinc oxide nanoparticles.

The researchers next dip-coated the modified wire with an electroluminscent polymer layer, consisting of a blend of a blue light emitting polymer (PF-B), ethoxylated trimethylopropane triacrylate (ETT-15) and lithium trifluoromethane sulfonate (LiTf).

Finally, the polymer-coated wire was wrapped in a layer of aligned carbon nanotubes. This was achieved by slowly rotating the wire with motor and winding a spinnable carbon nanotube array around it.

So far only blue wires have been created but it should be possible to make a range of colours.

Fudan University - a fibre of a polymer light-emitting electrochemical cell (PLEC)

Figure: Fudan University - a fibre of a polymer light-emitting electrochemical cell (PLEC)

When a voltage is applied – the steel wire core acts as the anode and the carbon nanotube sheet as the cathode – the polymer emits light. The researchers were able to fabricate fibres that were several centimetres long. They wove a number of such fibres into a fabric sample to demonstrate the fibres’ flexibility and strength. The colour of the display can be controlled by using a range of fibres that each emits a different colour.

Zhitao Zhang said, "We incorporated about six fibres into a sample of fabric several centimetres square." Zhitao added, "The fibre-shaped PLEC is flexible, and its brightness was maintained at above 90% of its maximum after bending with a radius of curvature of 6mm for 100 cycles."
Zhitao Zhang said, "The fabrication processes used to create the PLEC fibres are relatively simple and inexpensive and lend themselves to scaling-up." He suggests "that the fibres could eventually find a role in biomedical applications, but concedes that before this can happen a number of hurdles need to be overcome. The luminance of the fibres drops away as soon as it has reached its maximum, so ways need to be found to make the system more stable. And for practical applications the fibres would need to be longer. ‘We are looking to improve the performance and lifetime of the fibres, by attempting to increase the electric conductivity of the electrode materials and seeking new light-emitting conjugated polymers."

Fashions on the catwalk could soon become a whole lot funkier with the development of new light-emitting threads that can be knitted or woven into textiles. Apart from the prospect of a waistcoat that can display illuminated images, the technology could find applications in medicine, its inventors say, with smart clothes that could be linked to diagnostic devices, allowing information about the wearer’s medical condition to be clearly communicated to the wearer or a health professional.

Source: Fudan University

A colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell

Zhitao Zhang | Kunping Guo, | Yiming Li, | Xueyi Li, | Guozhen Guan, | Houpu Li, | Yongfeng Luo, | Fangyuan Zhao, | Qi Zhang, | Bin Wei, | Qibing Pei | Huisheng Peng

Nature Photonics | (2015) | doi:10.1038/nphoton.2015.37

Received 17 December 2014 | Accepted 11 February 2015 | Published online 23 March 2015

Abstract

The emergence of wearable electronics and optoelectronics requires the development of devices that are not only highly flexible but can also be woven into textiles to offer a truly integrated solution. Here, we report a colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell (PLEC). The fibre-shaped PLEC is fabricated using all-solution-based processes that can be scaled up for practical applications. The design has a coaxial structure comprising a modified metal wire cathode and a conducting aligned carbon nanotube sheet anode, with an electroluminescent polymer layer sandwiched between them. The fibre shape offers unique and promising advantages. For example, the luminance is independent of viewing angle, the fibre-shaped PLEC can provide a variety of different and tunable colours, it is lightweight, flexible and wearable, and it can potentially be woven into light-emitting clothes for the creation of smart fabrics.

Z Zhang et al, Nat. Photon., 2015, DOI: 10.1038/nphoton.2015.37

www.fudan.edu.cn   

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