Advanced wearable display technologies using perovskite quantum wires

By creating full-colour fibre light-emitting diodes (Fi-LEDs) based on perovskite quantum wires (PeQWs), the team has overcome long-standing challenges, paving the way for more flexible, durable, and high-performance wearable electronics.

Exploring fibre LEDs

The exploration of fibre LEDs, particularly for wearable applications, stems from the increasing demand for flexible and portable electronic devices. Traditional rigid LEDs, while effective, are not suitable for integration into fabrics or wearable materials due to their lack of flexibility. This has driven research into alternatives like fibre LEDs, which can be woven into textiles, offering new possibilities for wearable displays, health monitoring systems, and more.

The key to achieving high-performance fibre LEDs lies in overcoming issues related to the fabrication and encapsulation of these devices. Challenges such as uneven coating, poor crystallisation of materials, and complex electrode deposition processes previously made it difficult to produce uniform and efficient light emission from fibre LEDs.

One of the main challenges in developing fibre LEDs has been the fabrication process. When using fibre-like substrates, issues such as gravity and surface tension can cause non-uniform coating of the light-emitting material, leading to inefficient light emission. Additionally, the crystallisation of the materials used in these LEDs has often been of low quality, further reducing their effectiveness. The deposition of electrodes on these flexible substrates has also been a complex process, making the manufacturing of reliable fibre LEDs difficult.

The breakthrough: perovskite quantum wires

The team at HKUST tackled these challenges by developing a novel approach using perovskite quantum wires. Perovskites are materials that have excellent light-emitting properties, including effective radiative carrier recombination (the process by which light is emitted), colour tunability, and the ability to be fabricated at relatively low temperatures.

The researchers grew these quantum wires on aluminium (Al) fibres using a template made of porous alumina membrane (PAM). This membrane has very small pores, which help in creating a uniform and high-density array of quantum wires. By using a roll-to-roll solution-coating process, they were able to achieve a nearly 100% filling ratio of the pores with the perovskite material, ensuring uniformity in the light-emitting properties of the fibres.

To further enhance the performance of these Fi-LEDs, the team encapsulated the devices in polydimethylsiloxane (PDMS), a flexible and waterproof material that also provides mechanical stability. This encapsulation allowed the Fi-LEDs to maintain their performance even when bent, stretched, or exposed to water, making them ideal for wearable applications.

The findings

The full-colour Fi-LEDs developed by the team exhibited excellent colour purity and brightness, with emission peaks at 625 nanometres (red), 512 nanometres (green), and 490 nanometres (sky blue). The devices also demonstrated good mechanical flexibility and durability, crucial for wearable technology.

This research opens up new possibilities for integrating advanced lighting and display technologies into wearable and flexible electronics. The ability to produce high-quality, flexible LEDs that can be woven into textiles or used in other unconventional forms could change the wearable electronics industry, leading to new applications in health monitoring, fashion, and more.

By addressing the challenges associated with fabrication and encapsulation, the team led by Professor Zhiyong Fan has created a new platform for flexible, durable, and high-performance wearable electronics. This breakthrough could pave the way for the next generation of wearable devices, offering enhanced functionality and integration into everyday life.