Smart Textile Lighting/Display System and Future Quantum Dot Light Emitting Diode

The aim of this research is to develop a smart textile system based on multifunctional input and output electronic fibre devices. Unlike planar/rigid display devices, this research proposes not only a novel device architecture but also its integration into a textile system by using conventional yarn-to-textile methodologies, such as weaving and knitting. Smart lighting/display textile with multifunctional fibre devices has great potential in numerous areas, including lighting, display, smart home and Internet of Thing (IoT). This thesis first introduces the existing technology in textile engineering, including conventional fibre material and textile fabrication technology followed by the latest development in smart textile, which covers topics of functional fibre materials and devices. Conductive yarn is the fundamental for fibre-electronics and smart textile. The developed silver-polyamide (Ag-PA) conductive fibre shows an excellent electrical conductivity and mechanical robustness up to 35% strain. The F-touch and F-RF fabricated from Ag-PA also exhibits an excellent bending durability. The Field- effect transistor (FET) based F-biosensor shows a threshold voltage V_TH of 0.9 V, an ON/OFF ratio of 10⁸, and a saturation mobility μ_sat of 8 cm²/V·s which is comparable to the state-of-the-art flexible transistors. The F-temperature and F- energy demonstrated the viability of true core-shell cylindrical structure device for temperature measurement and energy storage that could withstand more than 900 bending cycles. As an output component, F-LEDs (fibre light-emitting diode) embedded 34-inch 6536-pixel full colour large area display represents the highest resolution full colour textile display reported to the date. The integrated smart textile has functions including touch detection, electrocardiogram (ECG) bio-signal measurement, temperature monitoring, far- field ultraviolet (UV) detection, wireless power transmission with RF signal, energy storage and video/image/information displaying. To further improve the display unit, a quantum dot light-emitting diode (QDLED) based textile display was developed. The electrode with lab synthesized silver nanowire (AgNW) shows a figure of merit (FoM) of 0.0014. The optimised MoO₃/Au electrode exhibits a transmittance of T₅₅₀= 81%, sheet resistance of Rs = 17.92 and a FoM of 0.0077. Both electrodes show a superior mechanical bending durability beyond the indium tin oxide (ITO) electrode. The optimisation was carried out on QDLED devices to ensure their performance meets the requirements for smart textile. The reduced phosphomolybdic acid hole injection layer (PMA-r HIL) based device exhibits a luminance that is comparable to the poly(3,4- ethylenedioxythiophene) with poly(4-sulfonate) (PEDOT:PSS) HIL based device and an even higher external quantum efficiency (EQE). The novel double layer PMA-r/PEDOT:PSS HIL device shows a remarkable 11.33% EQE. A remarkable lifetime of T₇₅ = 1019 h is achieved using MoO₃/Au/PMA-r device. The bending test also shows such device is able to maintain its luminance over 15000 cd/m² after 500 bending cycles at a bending radius of 5 mm. On the system level, a novel lateral driving architecture for smart textile display was developed and examined. The innovative architecture greatly simplifies the interconnection and tackles the resolution and stability issue encountered by other textile display architecture. The woven textile display is the world’s first full color QDLED textile display with high pixels per inch (PPI) scalability.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2022

Author dc:creator

• Yang, Jiajie

Advisor dc:contributor.advisor

• Kim, Jong Min

• Display
• Quantum Dot
• Smart Textile

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/cfd747f3-cd18-45dd-be1b-1f798ab8f796/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.99831

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/353786