Light fidelity (LiFi), which is emerging as a compelling technology paradigm shifting the common means of high-capacity wireless communication technologies, requires wearable and full-duplex compact design because of its great significance in smart wearables as well as the ‘Internet of Things’. However, the construction of the key component of wearable full-duplex LiFi, light-emitting/detecting bifunctional fibres, is still challenging because of the conflicting process between carrier separation and recombination, as well as the highly dynamic film-forming process. Here, we demonstrate light-emitting/detecting bifunctional fibres enabled by perovskite QDs with hybrid components. The hybrid perovskite inks endow fibres with super-smooth QD films. This, combined with the small exciton binding energy and high carrier mobility of perovskite QDs, enables successful integration of electroluminescence and photodetection into monofilaments. The bifunctional fibres possess the narrowest electroluminescence full width at half maximum of ~19 nm and, more importantly, the capability for simultaneously transmitting and receiving information. The successful fabrication of narrow emission full-duplex LiFi fibres paves the way for the fabrication and integration of low crosstalk interoperable smart wearables.
LiFi technology: Hybrid fibres for bidirectional communication with light Light-emitting and detecting fibres incorporating ‘quantum dot’ structures composed of material called perovskite suitable for wireless communication using light, known as light fidelity (LiFi). The fibres, which should be suitable for developing wearable smart devices, have been developed by Qingsong Shan and colleagues at Nanjing University of Science and Technology, China, with co-workers at Nanjing University of Posts and Telecommunications, China. Quantum dots are tiny nanoparticles that are sufficiently small for quantum mechanical effects to permeate across their entire structure. Perovskites share the crystal structure of the natural mineral perovskite, with varying chemical compositions that open up a wide range of new properties. The perovskite quantum dots are coated as an active layer on polyethylene terephthalate (PET) layers, creating a fibrous device with the much sought property of simultaneously transmitting and receiving information.