Effect of UV illumination on perylene-doped luminescent solar concentrators: a cautionary tale

The luminescent solar concentrator has the potential of widespread use as a generator of electricity from sunlight well-suited for use in the urban environment owing to its adaptability in shape and coloration. The device performance is heavily dependent on the ability to transport light long distances to the edges. A common organic luminophore used in the device is based on a perylene core. In this work, we describe an overlooked effect of UV illumination on the appearance and efficiency of these devices. An additional absorption peak appears upon polymerization under intense UV in nitrogen atmosphere which significantly reduces the edge emissions from the device. The additional absorbance peak disappears after exposure to air, indicating the presence of a radical anion being formed during the UV light exposure. This suggests newly-produced LSC devices should be allowed to stand a period of time under ambient conditions before their performance characteristics are determined, which could have implications in potential future commercialization of the technology

Photoresponsive polymer hydrogel coatings that change topography

This chapter provides a brief overview of the principles as well as the potential applications of photoresponsive hydrogel films, which change surface topography. It discusses the operating mechanisms that lead to topographical changes. Changes in topography can affect the wettability of a surface, which is an interesting characteristic for making self‐cleaning coatings. The chapter also discusses polymer films that are useful for the development of self‐cleaning films. It then discusses responsive materials, for cell culturing and microfluidics applications. The chapter further shows that appealing photoresponsive polymer hydrogel coatings that change topography can be fabricated, which holds great promise in a variety of fields ranging from microfluidic devices to biomedical applications. When the structures of the topography are in the micrometer size regime, they influence the wettability of the surface. Two types of wetting can be defined: Wenzel and Cassie‐Baxter

Initiation and recovery of damage initiated by UV irradiation in luminescent solar concentrators processed in ambient conditions

Photopolymerization of thin, dye-doped acrylate-based layers under ambient conditions often requires high concentrations of photoinitiators. The radical storm created during polymerization has been shown to cause damage to the embedded fluorescent dyes; some of this damage is repaired upon exposure to air, but a fraction of the damaged molecules do not repair. This work presents a more detailed optical study of the environmental effects, nature of the initiator, and resulting fluorescence of the dye molecules caused by photopolymerization, all factors necessary to understand and control to allow ambient inkjet printing of these luminescent species

Effect of UV illumination on perylene-doped luminescent solar concentrators:a cautionary tale

\u3cp\u3eThe luminescent solar concentrator has the potential of widespread use as a generator of electricity from sunlight well-suited for use in the urban environment owing to its adaptability in shape and coloration. The device performance is heavily dependent on the ability to transport light long distances to the edges. A common organic luminophore used in the device is based on a perylene core. In this work, we describe an overlooked effect of UV illumination on the appearance and efficiency of these devices. An additional absorption peak appears upon polymerization under intense UV in nitrogen atmosphere which significantly reduces the edge emissions from the device. The additional absorbance peak disappears after exposure to air, indicating the presence of a radical anion being formed during the UV light exposure. This suggests newly-produced LSC devices should be allowed to stand a period of time under ambient conditions before their performance characteristics are determined, which could have implications in potential future commercialization of the technology.\u3c/p\u3

Tuning microfluidic flow by pulsed light oscillating spiropyran-basedpolymer hydrogel valves

A method for microfluidic flow control based upon polymer hydrogel valves with rapid and reversible actuation properties is described. The platform allows for contactless optical flow control based upon pulsing light, resulting in a forced oscillating and control over the valve through photo-isomerisation of a spiropyran derivative, co-polymerised within an N-isopropylacrylamide (NIPAm) hydrogel. Application of pulsed light (450 nm) to the valves allows the valves to be held at an intermediate position for extended periods of time. Varying the extent of pulsing of the light source enables the flow rate to be regulated within a microfluidic flow rate range of 0–27 μL/min. Due to the pulsed light, a small period change in the flow rate is observed that corresponds to the pulse sequence as a corresponding oscillation in the hydrogel valves