Full-colour fibre LEDs based on perovskite quantum wires

A team of researchers from the Hong Kong University of Science and technology (HKUST) has developed full-colour fibre light-emitting diodes using perovskite quantum wires (PeQWs), paving the way for innovative wearable lighting and display devices.

Fibre light-emitting diodes (Fi-LEDs) are a key component in the realm of flexible LEDs because of their compatibility with textile fabrication and spatial luminance uniformity. Metal halide perovskites (MHPs) are promising light-emitting materials for next-generation LEDs because of their superior optoelectronic properties.

Despite the potential, the fabrication of MHP-based Fi-LEDs faces challenges such as gravity- and surface tension-induced non-uniform coating, low-quality crystallisation and a complex electrode deposition process, which all culminate in uneven and inefficient light emission.

To tackle these issues, the researchers, led by Professor Zhiyong Fan, used porous alumina membrane (PAM) templates on thin aluminium fibres. The PAM, with an ultra-small pore size of approximately 5 nm, was fabricated on aluminium fibres using a roll-to-roll solution-coating process. The MHP precursor solution was filled into the PAM channels, followed by a surrounding annealing procedure to ensure spatially uniform solvent vaporisation and MHP crystallisation. This method enabled the uniform growth of PeQW arrays and minimised the formation of unwanted thin-film structures on the PAM surface.

The researchers demonstrated the fabrication of full-colour Fi-LEDs with emission peaks at 625 nm (red), 512 nm (green) and 490 nm (sky blue). The fabricated fibres also exhibited good bendability and stretchability, making them suitable for textile lighting applications. A “night scene” of Victoria Harbour was created using PeQWs with halide gradient-induced colour transitions, highlighting the versatility and aesthetic potential of the Fi-LEDs.

The research findings represent a significant advancement in the field of Fi-LEDs; future developments could focus on enhancing the efficiency and stability of Fi-LEDs, exploring new perovskite compositions for a broader range of emission colours and integrating these devices into commercial textile products.

“The combination of quantum confinement effect and the passivation from the 3D porous alumina membrane structure has enabled us to achieve outstanding photoluminescence and electroluminescence efficacy. Our innovative approach for fibre LEDs opens up new possibilities for fabricating unconventional 3D-structured lighting sources, paving the way for advanced wearable display technologies,” Fan said.

Image credit: iStock.com/Jorge_53