A Review on Electrospun Luminescent Nanofibers: Photoluminescence Characteristics and Potential Applications

Background: Photoluminescent materials have been used for diverse applications in the fields of science and engineering, such as optical storage, biological labeling, noninvasive imaging, solid-state lasers, light-emitting diodes, theranostics/theragnostics, up-conversion lasers, solar cells, spectrum modifiers, photodynamic therapy remote controllers, optical waveguide amplifiers and temperature sensors. Nanosized luminescent materials could be ideal candidates in these applications. Objective: This review is to present a brief overview of photoluminescent nanofibers obtained through electrospinning and their emission characteristics. Methods: To prepare bulk-scale nanosized materials efficiently and cost-effectively, electrospinning is a widely used technique. By the electrospinning method, a sufficiently high direct-current voltage is applied to a polymer solution or melt; and at a certain critical point when the electrostatic force overcomes the surface tension, the droplet is stretched to form nanofibers. Polymer solutions or melts with a high degree of molecular cohesion due to intermolecular interactions are the feedstock. Subsequent calcination in air or specific gas may be required to remove the organic elements to obtain the desired composition. Results: The luminescent nanofibers are classified based on the composition, structure, and synthesis material. The photoluminescent emission characteristics of the nanofibers reveal intriguing features such as polarized emission, energy transfer, fluorescent quenching, and sensing. An overview of the process, controlling parameters and techniques associated with electrospinning of organic, inorganic and composite nanofibers are discussed in detail. The scope and potential applications of these luminescent fibers also conversed. Conclusion: The electrospinning process is a matured technique to produce nanofibers on a large scale. Organic nanofibers have exhibited superior fluorescent emissions for waveguides, LEDs and lasing devices, and inorganic nanofibers for high-end sensors, scintillators, and catalysts. Multifunctionalities can be achieved for photovoltaics, sensing, drug delivery, magnetism, catalysis, and so on. The potential of these nanofibers can be extended but not limited to smart clothing, tissue engineering, energy harvesting, energy storage, communication, safe data storage, etc. and it is anticipated that in the near future, luminescent nanofibers will find many more applications in diverse scientific disciplines.