Photoluminescent Nanofibers for Solid-State Lighting Applications

Abstract

Figure 13. Typical spectral radiant flux obtained using the PLN technology. This light source was a neutral white color. Figure 12. Through a judicious choice of nanofiber properties and luminescent particle coatings, virtually any point on the chromaticity axis can be produced. In this example, a blue (450 nm) LED is used to pump green and red PLNs to produce various colors. Figure 2. SEM images of (A) smooth PMMA nanofibers and (B) porous PMMA nanofibers produced through electrospinning.A BAs the solution flows to the electrode, the high electric field deforms each drop of the polymer solution into a conical shape known as a Taylor cone. Above a threshold limit, the electrical forces overcome the surface tension of the solution, and a fine, charged jet is ejected from the electrode and ultimately deposits nanofibers on a grounded substrate.In SSL applications, we have found that nanofiber mats serve the following functions:Provide optical filtering of the pump radiation ElectrospinningPolymer nanofibers are macro-sized objects with nanoscale features. The length (>> microns) of the nanofibers imparts macro-scale properties, while their diameter (50 nm-500 nm) imparts nanomaterial behavior. In addition, other nanoscale features such as surface pores or nanoparticles (e.g., luminescent quantum dots [QDs]) can be incorporated into the nanofiber to provide special physical and optical properties.Nanofibers are typically formed using the process of electro spinning, which involves applying a high voltage to an electrode in contact with a reservoir of polymer solution. The quantum dots used in the spray coating solution have the following properties:The QD consists of a semiconducting CdSe core that absorbs short wavelengths and emits longer • wavelengths. The emission color depends on the size of this core.A ZnS shell surrounds the core and provides environmental stability. • A long-chain amine coordination sphere is attached to the ZnS shell to provide compatibility • with various solvents and polymers. AbstractPhotoluminescent nanofibers (PLNs) can be formed by combining electrospun polymeric nanofibers and luminescent particles such as quantum dots (QDs). The physical properties of PLNs are dependent upon many different nanoscale parameters associated with the nanofiber, the luminescent particles, and their interactions. By understanding and manipulating these properties, the performance of the resulting optical structure can be tailored for desired end-use applications. For example, the quantum efficiency of QDs in the PLN structure depends upon multiple parameters including QD chemistry, the method of forming the PLN nanocomposites, and preventing agglomeration of the QD particles. This is especially important in solution-based electrospinning environments where some common solvents may have a detrimental effect on the performance of the PLN. With the proper control of these parameters, high quantum efficiencies can be readily obtained for PLNs. Achieving high quantum efficiencies is critical in applicatio...

Photoluminescent materials based on PMMA and a highly-emissive octahedral molybdenum metal cluster complex

“…Polymer fibres produced from PMMA doped with photoluminescent entities are of particular interest. 28 Applications of such fibres include use in lasers, [29][30][31] optical waveguides, 32,33 gas sensors, 34 solid-state lighting technologies, 35,36 etc. Moreover, the earlier work of Kirakci et al 14 showed that that fibres obtained by electrospinning a solution of polyurethane and (Bu 4 N) 2 [{Mo 6 I 8 }(OOCCF 3 ) 6 ] acquired the ability of the metal cluster complex to generate singlet oxygen.…”

Recent Advances in Luminescent Nanomaterials for Solid State Lighting Applications

“…Photoluminescent nanofibers (PLNs) are a new class of materials for SSL applications that can be created by combining polymeric nanofibers and luminescent nanoparticles such as QDs [126]. When dispersed across a flexible panel, PLNs are able to diffuse light and provide panel lighting from inorganic LEDs.…”

Full-Color Emissive Poly(Ethylene Oxide) Electrospun Nanofibers Containing a Single Hyperbranched Conjugated Polymer for Large-Scale, Flexible Light-Emitting Sheets

“…[ 36,37 ] Several studies on white light-emitting fi ber have been reported recently. [38][39][40][41] Moveover, nanofi ber lighting improvement technology (NLITe) from RTI International reported on the possible development of photoluminescent nanofi bers with white light for solid-state lighting applications, through a combination of electrospun nanofi bers and luminescent particles such as quantum dots. [ 40 ] Therefore, fabrication of white lightemitting fi bers using a single emitting molecule is still challenging due to their potential, such as simple and inexpensive technique and energy effi ciency.…”

“…Among the FLESs based on light-emitting nanofi bers, solid-state lighting can offer diverse advantages by use of light-emitting nanofi bers from electrospinning, such as high color rendering index and simple design for new lighting with various shapes. [ 40 ] Therefore, we attempted to fabricate electrospun fi ber-based FLESs containing fl uorescent hyperbranched conjugated polymers (HCPs) as lightemitting materials. HCPs were chosen as the light-emitting materials because of their special properties, such as higher solubility and more attractive processability, than their linear analogues.…”